Microsoft released version 1.0 of Internet Explorer as a part of the Windows 95 Plus Pack add-on. According to former Spyglass developer Eric Sink, Internet Explorer was based not on NCSA Mosaic as commonly believed, but on a version of Mosaic developed at Spyglass (which itself was based upon NCSA Mosaic). Microsoft quickly released several successive versions of Internet Explorer, bundling them with Windows, never charging for them, financing their development and marketing with revenues from other areas of the company. This period of time became known as the browser wars, in which Netscape Communicator and Internet Explorer added many new features and went through many version numbers (not always in a logical fashion) in attempts to outdo each other. But Internet Explorer had the upper hand, as the amount of manpower and capital dedicated to it eventually surpassed the resources available in Netscape's entire business. By version 3.0, IE was roughly a feature-for-feature equivalent of Netscape Communicator, and by version 4.0, it was generally considered to be more stable on Windows than on the Macintosh platform. Microsoft also targeted other Netscape products with free workalikes, such as the Internet Information Server (IIS), a web server that was bundled with Windows NT.