Internet Explorer 1.0/2.0/3.0
Anyway, I first used Netscape Navigator[2003], then IE 6[2006], then I moved to IE 8[2009], then I moved to Firefox 3.6[2010], then I moved to IE 9[2011] after that I moved to Chrome 25/Firefox 19[2013/14] and now I only use Chrome 33[March 2014-].