When it comes to visiting web pages, not all pages are created the same. You have to remember that when a particular website is developed, it was created at a particular time and was developed for rendering in the available browsers at that time. There are many websites still out there today which were developed 10 to 15 years ago and in most browsers, the markup of the HTML is not really rendered anymore. For these types of websites, the concept of Quirks Mode was developed.
This quirks mode was created as a means of maintaining backwards compatibility with older development languages and releases. While it seems as though every single year the W3C releases new compliance standards, and while new versions of the popular browsers are built upon these standards, the ability to render older websites means having to render a page which is not compliant to the standards set by the World Wide Web Consortium.
In the development of a website, you have two basic portions. The first part is that of the structure which is controlled through HTML. Even if you are using the latest dynamically driven website content management system, the output rendered to the browser will always be in HTML. Irregardless of whether the website is developed using PHP, Perl, Python, ASP or any other of the many possible languages, the part that the browser sees will always be HTML.
The second portion of a website is the appearance portion and for this the use of cascading style sheets is the standard. Before the days of the CSS file, all rendering of the appearance of a website was done through the HTML code. You would have to use tags like and much more to render the appearance. However today, the CSS file is used to do this and it takes up a lot less space and uses less bandwidth compared to using HTML for the same purpose.
Furthermore, in the past, web developers were prone to develop for specific browsers. Matter of fact this still occurs today. While some developers made sites specifically designed for Internet Explorer, the Mozilla FireFox browse may not render the page correctly. The same can be true in reverse. The only way for one to view a website as it was intended to look was through the particular browser it was developed for. As a result, the need for this quirks mode became increasingly apparent. As millions upon millions of new websites were added to the internet every year, ensuing that they were all compliant to W3C standards became a next to impossible task which is where the quirks mode comes into play.
In order to maintain this cross compatibility as well as backwards compatibility, the quirks mode allows the browser to guess the proper way to render a page rather than following by the standards strictly. Only a website which was developed to the standards strictly has the option of displaying the strict version of the source code for the browser to read. When it does not say to render it using “Strict” then the browser jumps into quirks mode and makes a guess as to the best way to render the page.
Original Authors: Nick
Edit Update Authors: M.A.Harris
Updated On: 04/03/2009