Windows Live Hotmail, formerly known as MSN Hotmail and commonly referred to simply as Hotmail, is a free webmail service of the Windows Live brand provided by Microsoft. It was called Windows Live Mail while it was a beta.

The Hotmail web-based email service was founded by Jack Smith and Sabeer Bhatia and launched in July of 1996. Hotmail was one of the first free webmail services. It was subsequently acquired by Microsoft in 1997 for an estimated $400 million, and rebranded as "MSN Hotmail". The current version, "Windows Live Hotmail" was officially announced on November 1, 2005 as an update to Microsoft's existing MSN Hotmail service. After a period of beta testing, it was officially released to new and existing users in the Netherlands on November 9, 2006 as a pilot market. The worldwide release was on May 7, 2007, and roll-out to all existing users was completed in October 2007.

Windows Live Hotmail features 5GB of storage but it grows as you need more. patented security measures, Ajax technology, and integration with Windows Live Messenger, Spaces, Calendar, and Contacts. It has over 270 million users worldwide (since February 1, 2008). It is available in 35 different languages, and is WINLive Hotmail's Aero Themes such as Yuko Kondo, Kat Leuzinger, Osmand Nosse, Klaus Haapaniemi, Red Nose Studios, Punga, Pomme Chan, Kustaa Saksi, Nanospore, Adhemas Batista, Kai and Sunny, Hvass Hannibal, Zune, Palmleaf, Metalwork.