HotMail is a seriously wack web mail service owned by Microsoft, and used by them as bait to assimilate unwitting souls into the .NET Passport programme. It has recently (in the last year or two) been rebranded MSN Hotmail and decked out in livery stolen from Sun's Forte for Java development environment. Hotmail is notoriously insecure, and has been cracked in spectacular fashion at least once (see above writeups). A Hotmail account is also a magnet for spam, some of it from Microsoft themselves (which you can't block).

Hotmail subjects you to between one and five centre-page advertisments before you can view your inbox, and after you perform any operation. Microsoft also use Hotmail as a crutch for their demonstrably inferior IM software, MSN Messenger, which is otherwise incapable of retaining offline messages.

I personally use Netscape's WebMail instead of Hotmail, mainly because it's less graphics-heavy, and doesn't print your password in plain text in its redirect URL. (You mean you didn't notice that...?) Hotmail's terms of use are pretty fucking hairy as well. It is probably a bad idea to correspond with the Patent Office via Hotmail.