1<?xml version="1.0" encoding="ISO-8859-1"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!-- 4 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 5 This file is generated from xml source: DO NOT EDIT 6 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 7 --> 8<title>Glossary - Apache HTTP Server</title> 9<link href="/style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> 10<link href="/style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> 11<link href="/style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="/style/css/prettify.css" /> 12<script src="/style/scripts/prettify.min.js" type="text/javascript"> 13</script> 14 15<link href="/images/favicon.ico" rel="shortcut icon" /></head> 16<body id="manual-page" class="no-sidebar"><div id="page-header"> 17<p class="menu"><a href="/mod/">Modules</a> | <a href="/mod/directives.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="/glossary.html">Glossary</a> | <a href="/sitemap.html">Sitemap</a></p> 18<p class="apache">Apache HTTP Server Version 2.4</p> 19<img alt="" src="/images/feather.gif" /></div> 20<div class="up"><a href="./"><img title="<-" alt="<-" src="/images/left.gif" /></a></div> 21<div id="path"> 22<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="./">Version 2.4</a></div><div id="page-content"><div id="preamble"><h1>Glossary</h1> 23<div class="toplang"> 24<p><span>Available Languages: </span><a href="/de/glossary.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> | 25<a href="/en/glossary.html" title="English"> en </a> | 26<a href="/es/glossary.html" hreflang="es" rel="alternate" title="Espa�ol"> es </a> | 27<a href="/fr/glossary.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a> | 28<a href="/ja/glossary.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | 29<a href="/ko/glossary.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> | 30<a href="/tr/glossary.html" hreflang="tr" rel="alternate" title="T�rk�e"> tr </a></p> 31</div> 32 33 <p>This glossary defines some of the common terminology related to Apache in 34 particular, and web serving in general. More information on each concept 35 is provided in the links.</p> 36 </div> 37<div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 38<div class="section"> 39<h2><a name="definitions" id="definitions">Definitions</a></h2> 40 41 <dl> 42 <dt><a name="accesscontrol" id="accesscontrol">Access Control</a></dt> 43 <dd>The restriction of access to network realms. In an Apache context 44 usually the restriction of access to certain <em>URLs</em>.<br /> See: <a href="howto/auth.html">Authentication, Authorization, and Access 45 Control</a> 46 </dd> 47 48 <dt><a name="algorithm" id="algorithm">Algorithm</a></dt> 49 <dd>An unambiguous formula or set of rules for solving a problem in a finite 50 number of steps. Algorithms for encryption are usually called 51 <dfn>Ciphers</dfn>. 52 </dd> 53 54 <dt><a name="apacheextensiontool" id="apacheextensiontool">APache 55 eXtension Tool</a> <a name="apxs" id="apxs">(apxs)</a></dt> 56 <dd>A perl script that aids in compiling <a class="glossarylink" href="/glossary.html#module" title="see glossary">module</a> sources into Dynamic Shared Objects 57 (<a class="glossarylink" href="/glossary.html#dso" title="see glossary">DSO</a>s) and helps install them in the 58 Apache Web server.<br /> 59 See: Manual Page: <code class="program"><a href="/programs/apxs.html">apxs</a></code> 60 </dd> 61 62 <dt><a name="apacheportableruntime" id="apacheportableruntime">Apache Portable Runtime</a> <a name="apr" id="apr">(APR)</a></dt> 63 <dd>A set of libraries providing many of the basic interfaces 64 between the server and the operating system. APR is developed 65 parallel to the Apache HTTP Server as an independent project.<br /> 66 See: <a href="http://apr.apache.org/">Apache Portable Runtime 67 Project</a> 68 </dd> 69 70 <dt><a name="authentication" id="authentication">Authentication</a></dt> 71 <dd>The positive identification of a network entity such as a server, a 72 client, or a user.<br /> 73 See: <a href="howto/auth.html">Authentication, Authorization, and Access 74 Control</a> 75 </dd> 76 77 <dt><a name="certificate" id="certificate">Certificate</a></dt> 78 <dd>A data record used for authenticating network entities such 79 as a server or a client. A certificate contains X.509 information pieces 80 about its owner (called the subject) and the signing <a class="glossarylink" href="/glossary.html#certificationauthority" title="see glossary">Certification Authority</a> (called 81 the issuer), plus the owner's <a class="glossarylink" href="/glossary.html#publickey" title="see glossary">public 82 key</a> and the 83 signature made by the CA. Network entities verify these signatures 84 using CA certificates.<br /> 85 See: <a href="ssl/">SSL/TLS Encryption</a> 86 </dd> 87 88 <dt><a name="certificatsigningrequest" id="certificatsigningrequest">Certificate Signing Request</a> 89 <a name="csr" id="csr">(CSR)</a></dt> 90 <dd>An unsigned <a class="glossarylink" href="/glossary.html#certificate" title="see glossary">certificate</a> for 91 submission to a <a class="glossarylink" href="/glossary.html#certificationauthority" title="see glossary">Certification 92 Authority</a>, which signs it with the <a class="glossarylink" href="/glossary.html#privatekey" title="see glossary">Private Key</a> of their CA 93 <em>Certificate</em>. Once the CSR is signed, it becomes a real 94 certificate.<br /> 95 See: <a href="ssl/">SSL/TLS Encryption</a> 96 </dd> 97 98 <dt><a name="certificationauthority" id="certificationauthority">Certification Authority</a> 99 <a name="ca" id="ca">(CA)</a></dt> 100 <dd>A trusted third party whose purpose is to sign certificates for network 101 entities it has authenticated using secure means. Other network entities 102 can check the signature to verify that a CA has authenticated the bearer 103 of a certificate.<br /> 104 See: <a href="ssl/">SSL/TLS Encryption</a> 105 </dd> 106 107 <dt><a name="cipher" id="cipher">Cipher</a></dt> 108 <dd>An algorithm or system for data encryption. Examples are DES, IDEA, RC4, 109 etc.<br /> 110 See: <a href="ssl/">SSL/TLS Encryption</a> 111 </dd> 112 113 <dt><a name="ciphertext" id="ciphertext">Ciphertext</a></dt> 114 <dd>The result after <a class="glossarylink" href="/glossary.html#plaintext" title="see glossary">Plaintext</a> is 115 passed through a <a class="glossarylink" href="/glossary.html#cipher" title="see glossary">Cipher</a>.<br /> See: <a href="ssl/">SSL/TLS Encryption</a> 116 </dd> 117 118 <dt><a name="commongatewayinterface" id="commongatewayinterface">Common 119 Gateway Interface</a> <a name="cgi" id="cgi">(CGI)</a></dt> 120 <dd>A standard definition for an interface between a web server and an 121 external program that allows the external program to service requests. 122 There is an <a href="http://www.ietf.org/rfc/rfc3875">Informational 123 RFC</a> which covers the specifics.<br /> 124 See: <a href="howto/cgi.html">Dynamic Content with CGI</a> 125 </dd> 126 127 <dt><a name="configurationdirective" id="configurationdirective">Configuration Directive</a></dt> 128 <dd>See: <a class="glossarylink" href="/glossary.html#directive" title="see glossary">Directive</a></dd> 129 130 <dt><a name="configurationfile" id="configurationfile">Configuration 131 File</a></dt> 132 <dd>A text file containing <a class="glossarylink" href="/glossary.html#directive" title="see glossary">Directives</a> 133 that control the configuration of Apache.<br /> 134 See: <a href="configuring.html">Configuration Files</a> 135 </dd> 136 137 <dt><a name="connect" id="connect">CONNECT</a></dt> 138 <dd>An HTTP <a class="glossarylink" href="/glossary.html#method" title="see glossary">method</a> for proxying raw data 139 channels over HTTP. It can be used to encapsulate other protocols, such as 140 the SSL protocol. 141 </dd> 142 143 <dt><a name="context" id="context">Context</a></dt> 144 <dd>An area in the <a class="glossarylink" href="/glossary.html#configurationfile" title="see glossary">configuration 145 files</a> where certain types of <a class="glossarylink" href="/glossary.html#directive" title="see glossary">directives</a> are allowed.<br /> 146 See: <a href="mod/directive-dict.html#Context">Terms Used to Describe 147 Apache Directives</a> 148 </dd> 149 150 <dt><a name="digitalsignature" id="digitalsignature">Digital 151 Signature</a></dt> 152 <dd>An encrypted text block that validates a certificate or other file. A 153 <a class="glossarylink" href="/glossary.html#certificationauthority" title="see glossary">Certification Authority</a> 154 creates a signature by generating a hash of the <em>Public Key</em> 155 embedded in a <em>Certificate</em>, then encrypting the hash with its own 156 <em>Private Key</em>. Only the CA's public key can decrypt the signature, 157 verifying that the CA has authenticated the network entity that owns the 158 <em>Certificate</em>.<br /> 159 See: <a href="ssl/">SSL/TLS Encryption</a> 160 </dd> 161 162 <dt><a name="directive" id="directive">Directive</a></dt> 163 <dd>A configuration command that controls one or more aspects of Apache's 164 behavior. Directives are placed in the <a class="glossarylink" href="/glossary.html#configurationfile" title="see glossary">Configuration File</a><br /> 165 See: <a href="mod/directives.html">Directive Index</a> 166 </dd> 167 168 <dt><a name="dynamicsharedobject" id="dynamicsharedobject">Dynamic 169 Shared Object</a> <a name="dso" id="dso">(DSO)</a></dt> 170 <dd><a class="glossarylink" href="/glossary.html#module" title="see glossary">Modules</a> compiled separately from the 171 Apache <code class="program"><a href="/programs/httpd.html">httpd</a></code> binary that can be loaded on-demand.<br /> 172 See: <a href="dso.html">Dynamic Shared Object Support</a> 173 </dd> 174 175 <dt><a name="environmentvariable" id="environmentvariable">Environment 176 Variable</a> <a name="env-variable" id="env-variable">(env-variable)</a></dt> 177 <dd>Named variables managed by the operating system shell and used to store 178 information and communicate between programs. Apache also contains 179 internal variables that are referred to as environment variables, but are 180 stored in internal Apache structures, rather than in the shell 181 environment.<br /> 182 See: <a href="env.html">Environment Variables in Apache</a> 183 </dd> 184 185 <dt><a name="export-crippled" id="export-crippled">Export-Crippled</a></dt> 186 <dd>Diminished in cryptographic strength (and security) in order to comply 187 with the United States' Export Administration Regulations (EAR). 188 Export-crippled cryptographic software is limited to a small key size, 189 resulting in <em>Ciphertext</em> which usually can be decrypted by brute 190 force.<br /> 191 See: <a href="ssl/">SSL/TLS Encryption</a> 192 </dd> 193 194 <dt><a name="filter" id="filter">Filter</a></dt> 195 <dd>A process that is applied to data that is sent or received by the 196 server. Input filters process data sent by the client to the server, 197 while output filters process documents on the server before they are sent 198 to the client. For example, the <code>INCLUDES</code> output filter 199 processes documents for <a class="glossarylink" href="/glossary.html#ssi" title="see glossary">Server Side 200 Includes</a>.<br /> 201 See: <a href="filter.html">Filters</a> 202 </dd> 203 204 <dt><a name="fully-qualifieddomain-name" id="fully-qualifieddomain-name">Fully-Qualified Domain-Name</a> 205 <a name="fqdn" id="fqdn">(FQDN)</a></dt> 206 <dd>The unique name of a network entity, consisting of a hostname and a 207 domain name that can resolve to an IP address. For example, 208 <code>www</code> is a hostname, <code>example.com</code> is a domain name, 209 and <code>www.example.com</code> is a fully-qualified domain name. 210 </dd> 211 212 <dt><a name="handler" id="handler">Handler</a></dt> 213 <dd>An internal Apache representation of the action to be performed when a 214 file is called. Generally, files have implicit handlers, based on the file 215 type. Normally, all files are simply served by the server, but certain 216 file types are "handled" separately. For example, the 217 <code>cgi-script</code> handler designates files to be processed as 218 <a class="glossarylink" href="/glossary.html#cgi" title="see glossary">CGIs</a>.<br /> 219 See: <a href="handler.html">Apache's Handler Use</a> 220 </dd> 221 222 <dt><a name="hash" id="hash">Hash</a></dt> 223 <dd>A mathematical one-way, irreversible algorithm generating a string with 224 fixed-length from another string of any length. Different input strings 225 will usually produce different hashes (depending on the hash function). 226 </dd> 227 228 <dt><a name="header" id="header">Header</a></dt> 229 <dd>The part of the <a class="glossarylink" href="/glossary.html#http" title="see glossary">HTTP</a> request and 230 response that is sent before the actual content, and that contains 231 meta-information describing the content. 232 </dd> 233 234 <dt><a name="htaccess" id="htaccess">.htaccess</a></dt> 235 <dd>A <a class="glossarylink" href="/glossary.html#configurationfile" title="see glossary">configuration file</a> that 236 is placed inside the web tree and applies configuration <a class="glossarylink" href="/glossary.html#directive" title="see glossary">directives</a> to the directory where it is 237 placed and all sub-directories. Despite its name, this file can hold 238 almost any type of directive, not just access-control directives.<br /> 239 See: <a href="configuring.html">Configuration Files</a> 240 </dd> 241 242 <dt><a name="httpd.conf" id="httpd.conf">httpd.conf</a></dt> 243 <dd>The main Apache <a class="glossarylink" href="/glossary.html#configurationfile" title="see glossary">configuration 244 file</a>. The default location is 245 <code>/usr/local/apache2/conf/httpd.conf</code>, but it may be moved using 246 run-time or compile-time configuration.<br /> 247 See: <a href="configuring.html">Configuration Files</a> 248 </dd> 249 250 <dt><a name="hypertexttransferprotocol" id="hypertexttransferprotocol">HyperText Transfer Protocol</a> 251 <a name="http" id="hhtp">(HTTP)</a></dt> 252 <dd>The standard transmission protocol used on the World Wide Web. Apache 253 implements version 1.1 of the protocol, referred to as HTTP/1.1 and 254 defined by <a href="http://ietf.org/rfc/rfc2616.txt">RFC 2616</a>. 255 </dd> 256 257 <dt><a name="https" id="https">HTTPS</a></dt> 258 <dd>The HyperText Transfer Protocol (Secure), the standard encrypted 259 communication mechanism on the World Wide Web. This is actually just HTTP 260 over <a class="glossarylink" href="/glossary.html#ssl" title="see glossary">SSL</a>.<br /> 261 See: <a href="ssl/">SSL/TLS Encryption</a> 262 </dd> 263 264 <dt><a name="method" id="method">Method</a></dt> 265 <dd>In the context of <a class="glossarylink" href="/glossary.html#http" title="see glossary">HTTP</a>, an action to 266 perform on a resource, specified on the request line by the client. Some 267 of the methods available in HTTP are <code>GET</code>, <code>POST</code>, 268 and <code>PUT</code>. 269 </dd> 270 271 <dt><a name="messagedigest" id="messagedigest">Message Digest</a></dt> 272 <dd>A hash of a message, which can be used to verify that the contents of 273 the message have not been altered in transit.<br /> 274 See: <a href="ssl/">SSL/TLS Encryption</a> 275 </dd> 276 277 <dt><a name="mime-type" id="mime-type">MIME-type</a></dt> 278 <dd>A way to describe the kind of document being transmitted. Its name 279 comes from that fact that its format is borrowed from the Multipurpose 280 Internet Mail Extensions. It consists of a major type and a minor type, 281 separated by a slash. Some examples are <code>text/html</code>, 282 <code>image/gif</code>, and <code>application/octet-stream</code>. In 283 HTTP, the MIME-type is transmitted in the <code>Content-Type</code> 284 <a class="glossarylink" href="/glossary.html#header" title="see glossary">header</a>.<br /> 285 See: <a href="mod/mod_mime.html">mod_mime</a> 286 </dd> 287 288 <dt><a name="module" id="module">Module</a></dt> 289 <dd>An independent part of a program. Much of Apache's functionality is 290 contained in modules that you can choose to include or exclude. Modules 291 that are compiled into the Apache <code class="program"><a href="/programs/httpd.html">httpd</a></code> binary are 292 called <dfn>static modules</dfn>, while modules that are stored 293 separately and can be optionally loaded at run-time are called 294 <dfn>dynamic modules</dfn> or <a class="glossarylink" href="/glossary.html#dso" title="see glossary">DSOs</a>. 295 Modules that are included by default 296 are called <dfn>base modules</dfn>. Many modules are available for Apache 297 that are not distributed as part of the Apache HTTP Server <a class="glossarylink" href="/glossary.html#tarball" title="see glossary">tarball</a>. These are referred to as 298 <dfn>third-party modules</dfn>.<br /> 299 See: <a href="mod/">Module Index</a> 300 </dd> 301 302 <dt><a name="modulemagicnumber" id="modulemagicnumber">Module Magic 303 Number</a> (<a name="mmn" id="mmn">MMN</a>)</dt> 304 <dd>Module Magic Number is a constant defined in the Apache source code that 305 is associated with binary compatibility of modules. It is changed when 306 internal Apache structures, function calls and other significant parts of 307 API change in such a way that binary compatibility cannot be guaranteed 308 any more. On MMN change, all third party modules have to be at least 309 recompiled, sometimes even slightly changed in order to work with the new 310 version of Apache. 311 </dd> 312 313 <dt><a name="openssl" id="openssl">OpenSSL</a></dt> 314 <dd>The Open Source toolkit for SSL/TLS<br /> 315 See <a href="http://www.openssl.org/">http://www.openssl.org/</a># 316 </dd> 317 318 <dt><a name="passphrase" id="passphrase">Pass Phrase</a></dt> 319 <dd>The word or phrase that protects private key files. It prevents 320 unauthorized users from encrypting them. Usually it's just the secret 321 encryption/decryption key used for <a class="glossarylink" href="/glossary.html#cipher" title="see glossary">Ciphers</a>.<br /> 322 See: <a href="ssl/">SSL/TLS Encryption</a> 323 </dd> 324 325 <dt><a name="plaintext" id="plaintext">Plaintext</a></dt> 326 <dd>The unencrypted text.</dd> 327 328 <dt><a name="privatekey" id="privatekey">Private Key</a></dt> 329 <dd>The secret key in a <a class="glossarylink" href="/glossary.html#publickeycryptography" title="see glossary">Public Key 330 Cryptography</a> system, used to decrypt incoming messages and 331 sign outgoing ones.<br /> 332 See: <a href="ssl/">SSL/TLS Encryption</a> 333 </dd> 334 335 <dt><a name="proxy" id="proxy">Proxy</a></dt> 336 <dd>An intermediate server that sits between the client and the <em>origin 337 server</em>. It accepts requests from clients, transmits those requests 338 on to the origin server, and then returns the response from the origin 339 server to the client. If several clients request the same content, the 340 proxy can deliver that content from its cache, rather than requesting it 341 from the origin server each time, thereby reducing response time.<br /> 342 See: <a href="mod/mod_proxy.html">mod_proxy</a> 343 </dd> 344 345 <dt><a name="publickey" id="publickey">Public Key</a></dt> 346 <dd>The publicly available key in a <a class="glossarylink" href="/glossary.html#publickeycryptography" title="see glossary">Public Key Cryptography</a> system, 347 used to encrypt messages bound for its owner and to decrypt signatures 348 made by its owner.<br /> 349 See: <a href="ssl/">SSL/TLS Encryption</a> 350 </dd> 351 352 <dt><a name="publickeycryptography" id="publickeycryptography">Public Key Cryptography</a></dt> 353 <dd>The study and application of asymmetric encryption systems, which use 354 one key for encryption and another for decryption. A corresponding pair of 355 such keys constitutes a key pair. Also called Asymmetric Cryptography. 356 <br /> 357 See: <a href="ssl/">SSL/TLS Encryption</a> 358 </dd> 359 360 <dt><a name="regularexpresion" id="regularexpresion">Regular Expression</a> 361 <a name="regex" id="regex">(Regex)</a></dt> 362 <dd>A way of describing a pattern in text - for example, "all the words that 363 begin with the letter A" or "every 10-digit phone number" or even "Every 364 sentence with two commas in it, and no capital letter Q". Regular 365 expressions are useful in Apache because they let you apply certain 366 attributes against collections of files or resources in very flexible ways 367 - for example, all .gif and .jpg files under any "images" directory could 368 be written as "<code>/images/.*(jpg|gif)$</code>". In places where 369 regular expressions are used to replace strings, the special variables 370 $1 ... $9 contain backreferences to the grouped parts (in parentheses) of 371 the matched expression. The special variable $0 contains a backreference 372 to the whole matched expression. To write a literal dollar sign in a 373 replacement string, it can be escaped with a backslash. Historically, the 374 variable & could be used as alias for $0 in some places. This is no 375 longer possible since version 2.3.6. Apache uses Perl Compatible Regular 376 Expressions provided by the <a href="http://www.pcre.org/">PCRE</a> 377 library. You can find more documentation about PCRE's regular expression 378 syntax at that site, or at 379 <a href="http://en.wikipedia.org/wiki/PCRE">Wikipedia</a>. 380 </dd> 381 382 <dt><a name="reverseproxy" id="reverseproxy">Reverse Proxy</a></dt> 383 <dd>A <a class="glossarylink" href="/glossary.html#proxy" title="see glossary">proxy</a> server that appears to the client 384 as if it is an <em>origin server</em>. This is useful to hide the real 385 origin server from the client for security reasons, or to load balance. 386 </dd> 387 388 <dt><a name="securesocketslayer" id="securesocketslayer">Secure Sockets 389 Layer</a> <a name="ssl" id="ssl">(SSL)</a></dt> 390 <dd>A protocol created by Netscape Communications Corporation for general 391 communication authentication and encryption over TCP/IP networks. The most 392 popular usage is <em>HTTPS</em>, i.e. the HyperText Transfer Protocol (HTTP) 393 over SSL.<br /> 394 See: <a href="ssl/">SSL/TLS Encryption</a> 395 </dd> 396 397 <dt><a name="servernameindication" id="servernameindication">Server Name 398 Indication</a> <a name="sni" id="sni">(SNI)</a></dt> 399 <dd>An SSL function that allows passing the desired server 400 hostname in the initial SSL handshake message, so that the web 401 server can select the correct virtual host configuration to use 402 in processing the SSL handshake. It was added to SSL starting 403 with the TLS extensions, RFC 3546. <br /> 404 See: <a href="ssl/ssl_faq.html">the SSL FAQ</a> 405 and <a href="http://www.ietf.org/rfc/rfc3546.txt">RFC 3546</a> 406 </dd> 407 408 <dt><a name="serversideincludes" id="serversideincludes">Server Side 409 Includes</a> <a name="ssi" id="ssi">(SSI)</a></dt> 410 <dd>A technique for embedding processing directives inside HTML files.<br /> 411 See: <a href="howto/ssi.html">Introduction to Server Side Includes</a> 412 </dd> 413 414 <dt><a name="session" id="session">Session</a></dt> 415 <dd>The context information of a communication in general.</dd> 416 417 <dt><a name="ssleay" id="ssleay">SSLeay</a></dt> 418 <dd>The original SSL/TLS implementation library developed by Eric A. 419 Young 420 </dd> 421 422 <dt><a name="subrequest" id="subrequest">Subrequest</a></dt> 423 <dd>Apache provides a subrequest API to modules that allows other 424 filesystem or URL paths to be partially or fully evaluated by 425 the server. Example consumers of this API are 426 <code class="directive"><a href="/mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>, 427 <code class="module"><a href="/mod/mod_autoindex.html">mod_autoindex</a></code>, and <code class="module"><a href="/mod/mod_include.html">mod_include</a></code>. 428 </dd> 429 430 <dt><a name="symmetriccryptophraphy" id="symmetriccryptophraphy">Symmetric 431 Cryptography</a></dt> 432 <dd>The study and application of <em>Ciphers</em> that use a single secret key 433 for both encryption and decryption operations.<br /> 434 See: <a href="ssl/">SSL/TLS Encryption</a> 435 </dd> 436 437 <dt><a name="tarball" id="tarball">Tarball</a></dt> 438 <dd>A package of files gathered together using the <code>tar</code> utility. 439 Apache distributions are stored in compressed tar archives or using 440 pkzip. 441 </dd> 442 443 <dt><a name="transportlayersecurity" id="transportlayersecurity">Transport 444 Layer Security</a> <a name="tls" id="tls">(TLS)</a></dt> 445 <dd>The successor protocol to SSL, created by the Internet Engineering Task 446 Force (IETF) for general communication authentication and encryption over 447 TCP/IP networks. TLS version 1 is nearly identical with SSL version 3.<br /> 448 See: <a href="ssl/">SSL/TLS Encryption</a> 449 </dd> 450 451 <dt><a name="uniformresourcelocator" id="uniformresourcelocator">Uniform 452 Resource Locator</a> <a name="url" id="url">(URL)</a></dt> 453 <dd>The name/address of a resource on the Internet. This is the common 454 informal term for what is formally called a <a class="glossarylink" href="/glossary.html#uniformresourceidentifier" title="see glossary">Uniform Resource Identifier</a>. 455 URLs are usually made up of a scheme, like <code>http</code> or 456 <code>https</code>, a hostname, and a path. A URL for this page might 457 be <code>http://httpd.apache.org/docs/2.4/glossary.html</code>. 458 </dd> 459 460 <dt><a name="uniformresourceidentifier" id="uniformresourceidentifier">Uniform Resource Identifier</a> 461 <a name="URI" id="URI">(URI)</a></dt> 462 <dd>A compact string of characters for identifying an abstract or physical 463 resource. It is formally defined by <a href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>. URIs used on the 464 world-wide web are commonly referred to as <a class="glossarylink" href="/glossary.html#url" title="see glossary">URLs</a>. 465 </dd> 466 467 <dt><a name="virtualhosting" id="virtualhosting">Virtual Hosting</a></dt> 468 <dd>Serving multiple websites using a single instance of Apache. <em>IP 469 virtual hosting</em> differentiates between websites based on their IP 470 address, while <em>name-based virtual hosting</em> uses only the name of the 471 host and can therefore host many sites on the same IP address.<br /> 472 See: <a href="vhosts/">Apache Virtual Host documentation</a> 473 </dd> 474 475 <dt><a name="x.509" id="x.509">X.509</a></dt> 476 <dd>An authentication certificate scheme recommended by the International 477 Telecommunication Union (ITU-T) which is used for SSL/TLS authentication.<br /> See: <a href="ssl/">SSL/TLS Encryption</a> 478 </dd> 479 </dl> 480</div></div> 481<div class="bottomlang"> 482<p><span>Available Languages: </span><a href="/de/glossary.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> | 483<a href="/en/glossary.html" title="English"> en </a> | 484<a href="/es/glossary.html" hreflang="es" rel="alternate" title="Espa�ol"> es </a> | 485<a href="/fr/glossary.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a> | 486<a href="/ja/glossary.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | 487<a href="/ko/glossary.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> | 488<a href="/tr/glossary.html" hreflang="tr" rel="alternate" title="T�rk�e"> tr </a></p> 489</div><div class="top"><a href="#page-header"><img src="/images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. 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