Internet Explorer

Internet Explorer was the default browser for Windows XP. It is now effectively useless as it dosen't support modern TLS. Even if you did the POSReady hacks, the rendering engine can't cope with HTML5.

Version 6
The most infamous version which was used for years after it was obsolete due to being used in businesses who made proprietary web apps. Also was widely used in China and South Korea.

Version 7
Brought tabbed browsing to IE. Was heavily influenced by the success of Firefox.

Version 8
Last version of IE for XP. Was three versions behind Windows 7 and 8.1 when XP support ended. Microsoft’s lack of development of IE saw them eventually abandon their own browser engine for a Chromium based one in later Windows versions.

Shell browsers
Due to the IE engine being embeddable it was widely used in shell browsers which used it as an ActiveX control. Common features were adding tabbed browsing before IE got native tabbed browsing.