tedster - 5:56 am on May 28, 2004 (gmt 0)

There's been some question (sometimes a lot of question) about what quirks mode is, and the parallel question, what standards mode is. For many web designers, these are still unknown words - so I hope we can clear some of this up and give a platform for further learning.

Up until version 6 browsers, there was a lot of non-standard rendering built into user agents. A lot of this behavior didn't conform to the W3C rendering recommendations at all, but it was what we worked with and we got very used to it.

And then came the move to standards, with Document Type Declarations (DTD) and all that. But how can new browsers handle those legacy pages all, over the web that depend on "quirky" behavior in order to look good?

That became the question, and the answer is "quirks" mode.

If a browser sees a full DTD as the FIRST element of a document, including the W3C URL for the details, then it renders the page in "standards" mode. Because standards are still relatively young, there is some variation from one browser to another, but it's usually minor.

But if a browser sees no DTD, or a partial DTD, then it goes into "quirks mode", which essentially means rendering the page the wrong way, but the way we were used to up until version 6.

What this all means in specific detail is way beyond the scope of one thread. But I thought it would be very useful to have this explanation and a set of references in one spot, to get people started out on the right foot if this is all new to them. More and more, you will see these two modes mentioned in threads.

REFERENCES

W3C Valid DTDs [w3.org]
Opera re: Quirks Mode [opera.com]
Mozilla re: Quirks Mode [mozilla.org]
Microsoft re: Quirks Mode [msdn.microsoft.com]
DTDs and FrontPage [msdn.microsoft.com]