Windows Internet Explorer 7, commonly abbreviated IE7, is a proprietary, graphical web browser released by Microsoft in late 2006 for Windows Vista, Windows XP SP2 and Windows Server 2003 SP1. Internet Explorer 7 is part of a long line of Internet Explorer versions and the first major version of the browser in over 5 years, coinciding with the release of Windows Vista. Its market share is increasing as it ships as the default browser in Vista and is offered as a replacement for Internet Explorer 6 on Windows XP via Windows Update. While sources are not in agreement as to IE7's global market share (estimates from three sources range from 23% to 44%) , when combined with IE6, the two browsers represent the majority of browsers worldwide.