This article could be expanded on and use more details, and needs them as much as XP-tan needs more RAM!
Internet Explorer is a web browser that was released on August 16th, 1995. Started as a project in 1994, IE took much of its source code from Spyglass Inc.'s Mosaic web browser, with Microsoft Internet Explorer (aka IE 1) being a reworked version of Mosaic. IE was bundled with Microsoft Plus! for Windows 95 and the OEM release of 95. IE 1.5 was released several months later for Windows NT. Microsoft providing it for free on their operating systems, however, resulted in a lawsuit from Spyglass (who they had licensed the code from), which was eventually settled in early 1997.
IE-tan is typically depicted as a teenaged girl with blue hair (in varying lengths, sometimes in pigtails, depending on version) and a white outfit. She is nervous, but also very enthusiastic, cheerful, and eager to please. As a nod to the security vulnerabilities, IE-tan is prone to panty-flashing (though not on purpose), and can sometimes freeze or crash. It is likely that she is friends with the other browsers (though they may sigh and laugh at her antics a bit), Outlook-tan and various Windows-tans (though they may not always like her that much). In addition, a group of fans created an IE-tan for IE 11, which was subsequently picked up and given more life by Microsoft Singapore, the creator of the Silverlight girls.