What is IIS and how does it work?
Internet Information Services (IIS):
Internet Information Services (IIS) is a flexible, general-purpose web server from Microsoft that runs on Windows systems to serve requested HTML pages or files.
An IIS web server accepts requests from remote client computers and returns the appropriate response. This basic functionality allows web servers to share and deliver information across local area networks (LAN), such as corporate intranets, and wide area networks (WAN), such as the internet.
A web server can deliver information to users in several forms, such as static web pages coded in HTML; through file exchanges as downloads and uploads; and text documents, image files and more.
How IIS works?
IIS works through a variety of standard languages and protocols. HTML is used to create elements such as text, buttons, image placements, direct interactions/behaviors and hyperlinks. The Hypertext Transfer Protocol (HTTP) is the basic communication protocol used to exchange information between web servers and users. HTTPS -- HTTP over Secure Sockets Layer (SSL) -- uses Transport Layer Security or SSL to encrypt the communication for added data security. The File Transfer Protocol (FTP), or its secure variant, FTPS, can transfer files.
Additional supported protocols include the Simple Mail Transfer Protocol (SMTP), to send and receive email, and the Network News Transfer Protocol, to deliver articles on Usenet.
Versions of IIS
IIS has evolved along with Microsoft Windows. Early versions of IIS arrived with Windows NT. IIS 1.0 appeared with Windows NT 3.51, and evolved through IIS 4.0 with Windows NT 4.0. IIS 5.0 shipped with Windows 2000. Microsoft added IIS 6.0 to Windows Server 2003. IIS 7.0 offered a major redesign with Windows Server 2008 (IIS 7.5 is in Windows Server 2008 R2). IIS 8.0 came with Windows Server 2012 (Windows Server 2012 R2 uses IIS 8.5). And IIS 10 arrived with Windows Server 2016 and Windows 10.
With each iteration of IIS, Microsoft has added new features and updated existing functionality. For example, IIS 3.0 added ASP for dynamic scripting; IIS 6.0 added support for IPv6 and improved security and reliability; and IIS 8.0 brought multi core scaling on non-uniform memory access hardware, centralized SSL certificate support and Server Name Indication.