Full Form of IIS:
Internet Information Services
IIS Full Form is Internet Information Services. IIS refers to one or a group of extensible internet servers that is created by Microsoft. It was initially released and introduced with the aim to provide additional capabilities to Windows NT family which includes Windows NT and Windows 2000 server operating systems. Microsoft released this server as a competitive product for Apache which is used in Unix / Linux based operating systems. IIS ensures faster web page serving to its users. It was formerly known as Internet Information Server.
Anonymous authentication, digest access authentication, basic access authentication, UNC authentication, integrated windows authentication, certificate authentication and .NET passport authentication are the authentication mechanisms that are used in the latest versions of IIS. IIS also provides security specifications like IP security, URL authorization, request filtering and client certificate mapping.
Along with all of these features, the latest version, IIS 8.5 offers SNI (Server Name Indication), multi-core scaling on NUMA hardware, ASP.NET 4.5 support, dynamic IP address restrictions, web socket protocol support, centralized SSL certificate support, CPU throttling, splash page during application initialization, enhanced logging, ETW logging, automatic certificate rebind, dynamic site activation and idle-worker process page out. IIS provides a set of extensive programs that are mainly used in building and administering a search engine or a website and web-based applications that use databases. IIS Express is the lightweight version of IIS and it is available as an unique freeware server.