Back in the old days, people had to use tables to position things on a web page. Often tables inside of tables inside of tables were required to get the right effect. Needless to say, this added a lot of extra markup tags to every web page, making it difficult to maintain.
Then, along came SEO – Search Engine Optimization. Web programmers and designers discovered that search engines were using the keywords listed in the title and the main heading (h1 element) of each page to calculate a ratio between key words and number of characters on the page. Having all those table tags greatly reduced the SEO ratio and pages that used table layout received a much lower SEO rating.
Here is a tutorial showing how to layout out a page with a two-column or three-column layout using CSS. This moves all of the styling and layout tags out of the SEO equation, leaving more undiluted text on the page. You can use these layouts as a starting point of your page design without having to build everything from scratch.