Microsoft Plus! is an expansion pack for the Microsoft Windows95, 98, and XP operating systems. Each new version adds new features such as games, themes, and screensavers. Plus! for Windows 95 also included the very first version of Internet Explorer. The Plus! series has been discontinued, as some of its features have been integrated into Windows Vista and later Windows versions. A similar expansion pack was available for owners of Windows Vista Ultimate known as Ultimate Extras, and is often described as a spiritual successor of Plus!.