I am surprised by how many sites still use tables for layout. This was a practice adopted during the “browser wars” because of the low acceptance of CSS – for complex designs the only method available was to use tables. This is no longer the case. Now with web standards and CSS sites can be designed as they were intended – using markup for the purposes the creators meant for them: h tags for headers, p tags for paragraphs, div/spans for non-semantic elements and, finally, tables solely for tabular data (think spreadsheets like excel). Then you use the CSS for design and layout of the site.

Getting off my “web standards” soapbox for a moment the main reasons you want to avoid using tables for layout is that they bloat your markup. This makes it difficult to change and update your site and it hurts your ratings in search engines. By using the correct tags you naturally tell search engine spiders what your content is – a keyword rich header, a content rich paragraph or a navigation list. This allows them to better match your site to keyword searches and increase your audience. You also don’t have to change multiple pages of markup when you want to redesign your site – you simply edit your CSS and never touch the markup.

There are some instances where you want to, and should, use a table.  When designing the table you still want to keep standards in mind. In the old days you would use inline tags like “align” or “valign” for td’s and “cellpadding” or “cellspacing” for the table itself. Now all of that can be done through the CSS. Simply place a class on the table – or use the containing element of the table and apply the rules that way.

For example if you have a table inside a div with class “mySite” you could vertically align the td’s simply by using the following rule:

.mySite table td { vertical-align: top }

If you had used valign = “top” on all of those elements and then later on you decided you wanted to change them to centered you would have to go back and either do it by hand or via a find and replace. Using CSS and web standards you could simply change that one rule and affect all of the elements. That is the true power of it.

In conclusion, the most important thing to remember is to only use tables for the purpose they were created for – tabular data. When using them for this also remember to use the least markup possible. No presentational elements should be present – only semantic elements like content and semantic images (one that add value like logos or photos rather than are used for display like rounded corner containers). Also, if you find yourself placing tables within tables reevaluate your markup – you’re probably using this to create layout or presentation and could get away with a single table and CSS to style it.

Random Tidbit: Having trouble selling web standards to your boss?  The Web Standards Project can help.  Plus they have probably the best example of a site using web standards in every facet – which makes sense.