One of the biggest news in the tech world today is that Internet Explorer 8 has passed the Acid2 Test. From the IE8 blog,
As a team, we’ve spent the last year heads down working hard on IE8. Last week, we achieved an important milestone that should interest web developers. IE8 now renders the “Acid2 Face” correctly in IE8 standards mode.
For those not in the know, the Acid2 Test was written to make it easy to test a browser's compliance with web standards like HTML4 and CSS2. There are 2 types of Acid2 Tests - one with data URLs and the other without. This was due to the fact that Internet Explorer and some other browsers do not support data URLs.
In a perfect world, browsers would have proper and consistent support for official web standards and you wouldn't need to worry about your users' browsers as long as your pages followed the official guidelines. The reason why this is such a big deal is because Internet Explorer has the largest market share and passing the test means that some time in the distant future, that perfect world may become a reality.
The ironic part about all this is that while internal builds of IE8 have passed the Acid2 Test, the Acid2 Test on The Web Standards Project site is now broken and will fail to render properly even in compliant browsers! For a working alternative, use the one found at the Acid2 Test author's site.