The good news is that the current version browsers have gotten their acts together in supporting the available HTML and XHTML markup standards. Some browser-specific tags are still rattling around out there, but at least they aren't crating any new ones.
The new challenge is consistent is support for Cascading style sheets. Fortunately, the full level 1 specification is supported by the latest browsers (and the vast majority of browsers in use). Unfortunately, there is still a bit of chaos around the implementation of level 2 features such as absolute positioning, and no browser currently supporters every available property and value in the CSS 2.1 Recommendation. Nearly every browser out there, even the standerds-con format versions, are known to have quirks and bugs, but all eyes turn to Microsoft Internet Explorer for consistent support, because it makes up the lion's share of web traffic. Browser bugs and the workarounds necessary for dealing with them are treated in detail.
The advantage of the standards
We're all still waiting for that ideal day when all browsers faithfully adhere to the W3C Recommendations. but that;s no reason to put off creating standards compliant content yourself. Standards offer wonderful benefits that you can begin taking advantage of right away.
Your web content will certainly be viewed by a variety of browsers and devices, in addition to the graphical browsers we're most familiar with today, it may be displayed by alternative devices such as mobile phones, hand held computers, or assistance device such as screen readers for the visually impaired. By creating well-structured and logically marked up documents according to the guidelines for accessibility, you provide a batter experience for the greatest number of users.
Future standards will build on current standards, therefore, content that is strictly compliant today will enjoy longevity into a day when deprecated elements and attributes are no longer supported. Everyone will need to part with their table based layouts eventually. Why not start building sites the right way immediately?
Simpler and faster development
For years, web developers have needed to jump through hoops to compensate for the differences in browser support, sometimes resorting to creating several different version of the whole site to cater to browser support quirks.
Properly marketing up the structure of documents and the strategic use of style sheets enable you to create one version of your content that serves all your visitors. And because the document controlling visual style is separate from the content, the design and editorial development can happen in tandem, potentially shortening production schedules. By cutting time from development schedules, standard compliance can make good business sense.
Faster download and display
Document that use nonstandard HTML to control presentation (such as table, font tag, and transparent image) tend to get bloated. Stripping our these elements and using style sheet for controlling presentation typically result in much smaller files that download more quickly and may add up to significant bandwidth saving, On top of that, modern browsers render pages faster in standards mode than in backward-compatible mode. Faster pages mean happier visitors.