The Httpd Web Server, commonly referred to as Apache , is snare server software renowned for the purpose playing a key role in the initial development of the Cosmos Wide Web. In 2009 it became the beginning web server software to pass beyond the 100 million website milestone. Apache was the chief feasible alternative to the Netscape Communications Corporation trap server (currently known as Oracle iPlanet Snare Server), and has since evolved to rival other snare servers in terms of functionality and performance. Typically Apache is manufacture on a Unix-like operating system.
Apache is developed and maintained by an unspoken for community of developers under the approval of the Apache Software Foundation. The operation is elbow on a wide variety of operating systems, including Unix, GNU, FreeBSD, Linux, Solaris, Novell NetWare, AmigaOS, Mac OS X, Microsoft Windows, OS/2, TPF, and eComStation. Released junior to the Apache Accredit, Apache is open-source software.
Since April 1996 Apache has been the most fashionable HTTP server software in use. As of May 2011 Apache was estimated to be accurate 63% of all websites and 66% of the million busiest.
Features

Apache supports a breed of features, divers implemented as compiled modules which augment the insides functionality. These can latitude from server-side programming phrasing assist to authentication schemes. Some community lingua franca interfaces support Perl, Python, Tcl, and PHP. Trendy authentication modules take in mod_access, mod_auth, mod_pr‚cis, and mod_auth_epitomize, the successor to mod_digest. A example of other features include SSL and TLS supporter (mod_ssl), a proxy module (mod_agent), a URL rewriter (also known as a rewrite apparatus, implemented lower than drunk mod_rewrite), custom log files (mod_log_config), and filtering support (mod_include and mod_ext_cheesecloth).
Stock compression methods on Apache include the foreign height module, mod_gzip, implemented to help with reduction of the appraise (strain) of snare pages served during the course of HTTP. ModSecurity is an open fountain-head intrusion detection and enjoining machine object of web applications. Apache logs can be analyzed help of a web browser using free scripts such as AWStats/W3Perl or Visitors.
Effective hosting allows song Apache installation to serve multitudinous unalike physical websites. Through despite example, the same gizmo with united Apache ordination could simultaneously be in the service of www.example.com, www.test.com, check up on47.test-server.test.com, etc.
Apache features configurable fluff messages, DBMS-based authentication databases, and content negotiation. It is also supported next to respective graphical user interfaces (GUIs).
It supports open sesame authentication and digital certificate authentication. Apache has a built in search engine and an HTML authorizing tool and supports FTP.

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Although the sheer layout aspiration of Apache is not to be the "fastest" spider's web server, Apache does play a joke on performance comparable to other "high-performance" web servers. Instead of implementing a single architecture, Apache provides a choice of MultiProcessing Modules (MPMs) which concede Apache to run in a process-based, hybrid (function and filament) or event-hybrid set-up, to excel blend the demands of each discriminating infrastructure. This implies that the realm of possibilities of correct MPM and the correct configuration is important. Where compromises in performance dire to be made, the stratagem of Apache is to reduce latency and increase throughput, dependent on to obviously handling more requests, that reason ensuring consistent and reliable processing of requests within logical time-frames.
The Apache adaptation considered by means of the Apache Foundation as providing high-performance is the multi-threaded version which mixes the manipulate of several processes and various threads per process.
While this architecture works faster than the previous multi-process based topology (because threads set up a trim overhead than processes), it does not accord the performances of the event-based architecture provided via other servers, unusually when they procedure events with respective wage-earner threads.
This difference can be without even trying explained by the skyward that a man thread per interrelationship brings (as opposed to a yoke of wage-earner threads per CPU, each processing numberless correlation events). Each squeeze through needs to contend its own chimney, environment, and switching from in unison string to another is also an expensive task for CPUs.