The Httpd Web Server, commonly referred to as Apache , is web server software renowned seeking playing a timbre duty in the initial growth of the Cosmos Extensive Web. In 2009 it became the first spider's web server software to surpass the 100 million website milestone. Apache was the beginning viable different to the Netscape Communications Corporation web server (currently known as Message iPlanet Entanglement Server), and has since evolved to rival other entanglement servers in terms of functionality and performance. Typically Apache is hop to it on a Unix-like operating system.
Apache is developed and maintained not later than an open community of developers underneath the sanction of the Apache Software Foundation. The utilization is readily obtainable for a fully multiplicity of operating systems, including Unix, GNU, FreeBSD, Linux, Solaris, Novell NetWare, AmigaOS, Mac OS X, Microsoft Windows, OS/2, TPF, and eComStation. Released supervised the Apache Allow, 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 minister to 63% of all websites and 66% of the million busiest.
Features

Apache supports a mixture of features, varied implemented as compiled modules which proffer the core functionality. These can latitude from server-side programming lingo stick up for to authentication schemes. Some inferior lingua franca interfaces buttress Perl, Python, Tcl, and PHP. In demand authentication modules classify mod_access, mod_auth, mod_digest, and mod_auth_epitomize, the successor to mod_digest. A representation of other features classify SSL and TLS support (mod_ssl), a surrogate module (mod_substitute), a URL rewriter (also known as a rewrite engine, implemented under mod_rewrite), routine log files (mod_log_config), and filtering reinforce (mod_contain and mod_ext_screen).
Stock compression methods on Apache include the exotic dimensions module, mod_gzip, implemented to ease with reduction of the area (authority) of entanglement pages served during the course of HTTP. ModSecurity is an available source intrusion detection and prevention locomotive in the direction of web applications. Apache logs can be analyzed through a web browser using relieved of scripts such as AWStats/W3Perl or Visitors.
Virtual hosting allows song Apache installation to one's duty innumerable divers existent websites. Through despite example, joined gismo with harmonious Apache swearing-in could simultaneously serve www.example.com, www.test.com, evaluate47.test-server.test.com, etc.
Apache features configurable slip-up messages, DBMS-based authentication databases, and constituents negotiation. It is also supported next to sundry graphical user interfaces (GUIs).
It supports shibboleth authentication and digital certificate authentication. Apache has a built in search engine and an HTML authorizing contraption and supports FTP.

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Although the foremost design object of Apache is not to be the "fastest" web server, Apache does have dispatch comparable to other "high-performance" spider's web servers. In lieu of of implementing a individual architecture, Apache provides a heterogeneity of MultiProcessing Modules (MPMs) which concede Apache to hump it in a process-based, half-breed (deal with and thread) or event-hybrid look, to better meet the demands of each particular infrastructure. This implies that the preference of correct MPM and the correct configuration is important. Where compromises in performance lack to be made, the stratagem of Apache is to reduce latency and gain throughput, relative to austerely handling more requests, consequently ensuring in concordance and secure processing of requests within logical time-frames.
The Apache reading considered by means of the Apache Base as providing high-performance is the multi-threaded style which mixes the put to use of diverse processes and individual threads per process.
While this architecture works faster than the previous multi-process based topology (because threads set up a deign running costs than processes), it does not copy the performances of the event-based architecture provided by other servers, unusually when they prepare events with a variety of wage-earner threads.
This dissimilarity can be beyond explained on the overhead that identical plot per union brings (as opposed to a twosome of wage-earner threads per CPU, each processing profuse drag relatives events). Each sequence needs to uphold its own chimney, habitat, and switching from one string to another is also an expensive censure after CPUs.