(IIS) Microsoft's web server and FTP server for Windows NT. IIS is intended to meet the needs of a range of users: from workgroups and departments on a corporate intranet to ISPs hosting websites that receive millions of hits per day. Features include innovative web publishing, customisable tools, wizards, customisable management tools, flexible administration options, and analysis tools. IIS makes it easy to share documents and information across a company intranet or the Internet, and is completely integrated with Windows NT Directory Services. IIS 1.0 was released for Windows NT 3.51 and had a limited feature set. IIS 2.0 was released with Windows NT 4.0 with a similar feature set to IIS 1.0. IIS 3.0 quickly followed with many additions including Active Server Pages (ASP), ISAPI and ADO 1.0. IIS 4.0 is built into Windows NT Server 4.0. It includes ASP 2.0, ISAPI and ADO 1.5. Rival servers include Apache and Netscape Enterprise Server.