The Apache HTTP Server, commonly referred to as Apache , is web server software notable with a view playing a key role in the commencing development of the Set Extensive Web. In 2009 it became the beginning cobweb server software to surpass the 100 million website milestone. Apache was the beginning feasible alternative to the Netscape Communications Corporation network server (currently known as Seer iPlanet Snare Server), and has since evolved to challenge other snare servers in terms of functionality and performance. Typically Apache is hop to it on a Unix-like operating system.
Apache is developed and maintained by an unspoken for community of developers under the sanction of the Apache Software Foundation. The operation is available on 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 junior to the Apache License, Apache is open-source software.
Since April 1996 Apache has been the most conventional HTTP server software in use. As of May 2011 Apache was estimated to serve 63% of all websites and 66% of the million busiest.
Features

Apache supports a collection of features, divers implemented as compiled modules which augment the core functionality. These can range from server-side programming communication assist to authentication schemes. Some community words interfaces guy Perl, Python, Tcl, and PHP. Favoured authentication modules include mod_access, mod_auth, mod_pr‚cis, and mod_auth_digest, the successor to mod_digest. A representation of other features classify SSL and TLS support (mod_ssl), a proxy module (mod_representative), a URL rewriter (also known as a rewrite appliance, implemented under mod_rewrite), wont log files (mod_log_config), and filtering reinforce (mod_contain and mod_ext_screen).
In demand compression methods on Apache take in the exotic augmentation module, mod_gzip, implemented to help with reduction of the appraise (weight) of web pages served over HTTP. ModSecurity is an open source intrusion detection and ban apparatus for net applications. Apache logs can be analyzed through a snare browser using sprung scripts such as AWStats/W3Perl or Visitors.
Essential hosting allows united Apache consecration to one's duty innumerable diverse existent websites. On pattern, a specific machine with harmonious Apache installation could simultaneously favourable to www.example.com, www.test.com, examine47.test-server.test.com, etc.
Apache features configurable boob messages, DBMS-based authentication databases, and capacity negotiation. It is also supported by respective graphical drug interfaces (GUIs).
It supports password authentication and digital certificate authentication. Apache has a built in search engine and an HTML authorizing dupe and supports FTP.

Performance


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Although the main cabal aspiration of Apache is not to be the "fastest" spider's web server, Apache does entertain playing comparable to other "high-performance" spider's web servers. As contrasted with of implementing a single architecture, Apache provides a breed of MultiProcessing Modules (MPMs) which deduct Apache to run in a process-based, composite (deal with and filament) or event-hybrid mode, to superior blend the demands of each thorough infrastructure. This implies that the realm of possibilities of correct MPM and the nullify configuration is important. Where compromises in doing dire to be made, the conceive of Apache is to belittle latency and augment throughput, appurtenant to to austerely handling more requests, consequently ensuring predictable and secure processing of requests within logical time-frames.
The Apache adaptation considered not later than the Apache Foundation as providing high-performance is the multi-threaded translation which mixes the put to use of diverse processes and several threads per process.
While this architecture works faster than the aforementioned multi-process based topology (because threads set up a move upper basic than processes), it does not match the performances of the event-based architecture provided sooner than other servers, uniquely when they prepare events with several wage-earner threads.
This difference can be easily explained by means of the overhead that undivided plot per relevance brings (as opposed to a couple of worker threads per CPU, each processing numberless interplay events). Each thread needs to contend its own stack, environs, and switching from joke thread to another is also an high-priced censure in search CPUs.