In July 1995 Microsoft released Internet Explorer 1.0 as an add-on to the Windows 95 operating system. By November of the same year, the company had produced IE 2.0 for both Apple Inc.'s Macintosh and Windows 32-bit operating systems. This release featured support for the virtual reality modeling language (VRML), browser “cookies” (data saved by Web sites within the user's browser), and secure socket layering (SSL). The success of IE and the rapidly expanding online world led Microsoft to produce several editions of the program in rapid succession. In August 1996 IE 3.0, designed for use with Windows 95, added important components such as Internet Mail and News (an e-mail and newsgroup client) and Windows Media Player, a computer graphics program that allowed users to view GIF (graphics interchange format) and JPEG (joint photographic experts group) files; IE 3.0 also supported MIDI (musical instrument digital interface) sound files. (Although new IE versions for the Macintosh often lag behind Windows releases, Microsoft has never discontinued its support for the Macintosh.) IE 4.0, which came out in 1997, was tightly integrated into the company's main operating systems, Windows 95, Windows 98, and Windows NT. This incarnation replaced Internet Mail and News with Outlook Express, a freeware version of Microsoft Office Outlook, the company's commercial e-mail and newsgroup client. Released in September 1998, IE 5.0 expanded Web design capabilities and allowed for further personalization. IE 6.0, released in 2001 and designed to work with the Windows XP operating system, featured more privacy and security options. IE 6.0 was Microsoft's primary Web browser until the 2006 development of IE 7.0, which was compatible with the Windows Vista operating system. IE 8.0, which was released in a beta (preliminary) version in 2008, added more support for Web 2.0 features.