Microsoft Internet Explorer is a web browser application created by Microsoft primarily for Microsoft Windows. It was initially based on Spyglass Mosaic. At various points, Internet Explorer was also available for MacOS, Solaris, and HP-UX.
At its 1995 release, Internet Explorer competed with the Mosaic web browser and Netscape Navigator. Home Internet access was still somewhat new and competed against proprietary services like CompuServe, AOL, and Microsoft's own MSN.
Microsoft aggressively and abusively positioned Internet Explorer as part of their "browser war" to eliminate all competition. Microsoft fiercely pushed third party products to bundle Internet Explorer, and web sites to work only in Internet Explorer.
In 1998, Microsoft was hit with an antitrust suit, much of which involved their browser bundling.
By around 2004, Microsoft had destroyed most of their competition, dominated the browser market, and let IE stagnate until Mozilla.org released Firefox.
After Internet Explorer 11, Microsoft supplanted IE with "Microsoft Edge" which eventually switched to the Google Chrome rendering engine. Something that would have been unthinkable back then.
Internet Explorer is freely redistributable. But is archived here, as much software (stupidly) requires it.
Internet Explorer 10 was bundled with Windows 8 and Windows Server 2012. It could be installed on Windows 7 and Windows Server 2008 R2.
In Windows 8 "Metro" mode, IE 10 includes a new minimal user interface for idiots that like running everything full screen.