An Overview of Acid2

Acid2 is a test case designed by the Web Standards Project to identify web page rendering flaws in browsers and authoring tools. We'll take a brief look at the standards-based test.

In 1998, a grass roots coalition of web designers started the Web Standards Project. According to their web site, "The Web Standards Project (WaSP) fights for standards that reduce the cost and complexity of development while increasing the accessibility and long-term viability of any site published on the Web."

To aid in helping browser producers become more compliant with World Wide Web Consortium(W3C) standards, they published a test called Acid2. This was a take on the original acid test developed by the W3C to show whether a browser was conformant with the CSS box model. While Acid2 does test to ensure that browsers adhere to the CSS box model, it also tests on a number of other standards such as hovering effects, PNG alpha transparency (a long time bug in Internet explorer) and CSS positioning.

If you proceed to the Acid2 test page, your browser should display the smiley face graphic displayed above. If there are problems with the display of the smiley, its likely your browser doesn't support some CSS layout standards correctly.

A number of people have pointed out that not all of the CSS used in the Acid2 test is legal; this was intentional to test how particular browsers handled invalid CSS.

Browser Support

To date, Safari and Opera are the only two major browsers to pass Acid2. It is widely believed that the next release versions of Internet Explorer (IE8) and Firefox (FF3) will both pass the test.

Conclusion

Although Acid2 is an excellent test of how standards-compliant your browser is, its hardly definitive. As the Web Standards Project itself is quick to point out: "Everything that Acid2 tests is specified in a Web standard, but not all Web standards are tested." and "Acid2 does not guarantee conformance with any specification." It's important to keep this in mind-while its a good sign if a browser passes Acid2, there are many other standards that browsers need to comply with.