Apache is web server type which is able to maintain work with more than one operating system. It supports the next OS: Linux, BSD, Mac OS, Microsoft Windows, Novell NetWare, BeOS. The main preferences of Apache are considered to be its reliability and flexibility of configuration. It allows to plug external modules for reporting data, use DBMS for user identification, modify messages about errors, etc. Supports IPv6. Apache has integrated mechanism of virtual hosts. It allows to provide full service of many websites on the only one IP address, displaying their own contents for each of them.