This question comes up every now and then and there is a debate on market share, ...etc. Some will point to w3schools, others to other sites. The fact is: it all depends on the audience of a given site. It varies widely depending on that: For what's its worth, here are my April statistics for browsers (all browsers with less than 1% share are ignored) Quasi Techie site MS Internet Explorer 64 % (61% is MS IE 6.0) Firefox 22.4 % Unknown 5.7 % Safari 3 % Mozilla 1.5 % Opera 1.3 % Non techie niche site (in line with Steven's general web stats). MS Internet Explorer 82.2 % (79% is MS IE 6.0) Firefox 10.6 % Unknown 2.5 % Safari 1.4 % Mozilla 1 % Just look at the MS IE vs FF. 64:22 in one case, and 82:10 in the other. MS IE is mostly 6.0, so 5.x has very little market share.