Internet Information Services (IIS) is a general purpose web server software package designed and managed by Microsoft. It is a flexible web server that runs on Windows systems to serve HTML pages or files requested by individual users.
The first version, IIS 1.0, was initially released as a free add-on for Windows NT 3.51, and subsequent iterations of IIS have been released alongside each new version of Microsoft Windows. IIS can host websites, web applications and services needed by users or developers and is the second-most common server on the Internet, behind only Apache HTTP.
Like other web servers, IIS is designed to accept requests from remote computers, process the request and return the appropriate response. This allows servers to share information over the Internet, local area networks and other wide area networks. An IIS server can deliver this information in a number of forms including HTML web pages, text documents, image files and other file exchanges as downloads and uploads.
The History of Microsoft Web Servers
The first Microsoft web server was created at the University of Edinburgh in Scotland. It was developed as a research project in the European Microsoft Windows NT Academic Centre (EMWAC) within the university and was originally distributed as freeware. That initial server was clearly unable to handle the volume of web traffic on the Microsoft website, and the company was forced to develop its own unique server. Thus, IIS (then called Internet Information Server) was born and released as an add-on for Windows NT 3.51.
In 1996, Microsoft released Windows NT 4.0 and IIS 2.0 was included with the software. Still in its relative infancy, that version of IIS was still very similar to the original package, with few changes included or necessary at the time. However, IIS development would begin to grow from that point, with IIS 3.0 would be included in the Service Pack 2 for Windows NT 4.0. This version of the software would introduce the world to the concept of the Active Server Pages (ASP) dynamic scripting environment.
Version 4.0 would introduce new administration features, but it was IIS 5.0, included with the new Windows 2000, that would begin to include major enhancements to ASP and other new features such as support for WebDAV and additional authentication methods. Windows Server 2003 would include IIS 6.0 and be released alongside Windows XP Professional x64 Edition.
IIS for a New Age
When Microsoft built its Windows Vista OS and Windows Server 2008, IIS saw a complete overhaul and rewrite. It included enhanced security and performance features, as well as increased support for the .NET Framework. Another important element of this version was the new IIS Manager which can still be used to track usage and troubleshoot issues from unusual exception rates to w3wp high CPU usage.
IIS 7.5 was included with Windows 7 and built upon many of the performance, analyzation and compatibility features created with the previous version. Versions 8.0 and 8.5 would add multicore scaling on non-uniform memory access hardware, centralized SSL certificate support and additional features designed for Windows Server 2012. The latest iteration, IIS 10 is included with Windows Server 2016 and Windows 10, and this version includes HTTP/2 support.
With each new version, Microsoft continues to add to its already dynamic web server systems, and future IIS updates promise to be uniquely suited for enterprise-class development and cloud-based applications.