Good news everyone! Microsoft has decided to make upgrading to Internet Explorer 7 mandatory by bundling the newer browser into a mid-February autoupdate. Now, you may say this is not "mandatory" in the true sense of the word, and you may be right, but this step on behalf of everyone's favorite megacompany is sure to bring IE6 closer to a single-digit market share percentage. Who knows, maybe one day soon you won't be required to test your HTML and CSS code against IE6?
Internet Explorer has long beeen the poster child of standards incompatibility. You could fashion a complex layout, according to W3C standards, and be fairly sure that it would display more or less correctly in Firefox, Safari or Opera. Internet Explorer 6, on the other hand, often was a pain in the neck because of its rendering engine bugs and de-facto ubiquitous presence in the home and office.
While the newer version is not without its own problems (no browser is), many consider it superior. Currently, Firefox, IE6 and IE7 are used by about 90% of the people online, and each of the three browsers gets roughly a third of that figure.