When you’re designing a Web page and you want it to be optimized for search engines, you need to set up the page content so that the most important parts of the document come first in the HTML.
Search Engines Read HTML Linearly
Search engine spiders crawl through your HTML and read it in the order that it’s written in the page. Most search engines give a slightly higher priority to text that appears towards the beginning or top of the HTML document. This is because search engines do not have human instincts to recognize what parts of the page are the most important or most relevant.
Put the Most Important Content First
When you build a Web page and optimize it for search engines, you want to put the most important content first in the HTML. This means things like navigation should come after your main content. The closer you can get your content to the body tag, the higher priority it will have in the search engines.
But the problem is that getting your content first can be difficult with most layouts. For example, if you create a 2-column layout with navigation on the left – a very common layout – the navigation will, by necessity, appear first in the HTML in a table. But with CSS, you can create a layout where the navigation appears to the left, but is in the HTML second.
Float Your Layouts
The easiest way to create a layout that allows the content to be first, but the navigation column to be wherever you would like it – on the right or left – is to float the columns. Simply place your content in the first division of your HTML, and float that to the right. Then place your navigation in the second division of your HTML and float it to the left. This also works very well when you want a large picture to be first for the visitors but the content to be first for the search engines.