If we have a bunch of nested DIVs. How is this better than the nested tables they replaced? Now the answer lies in the way the tag was intended to be used. DIVs imply a logical and structural grouping. Even when they are nested they remain structural markup. In our example we grouped images with their captions (first level), and then grouped these image/caption pairs with similar image/caption pairs (second level). These are both examples of structural grouping that is handled much better by the DIV tag.

Whenever, tables imply a relationship between column and/or row headers, and the data in the table cells. When we use them for layout, we lose the structural semantics of a table. And we are back to using HTML for layout. Nesting tables only compounds the problem and as well now a days its not ideal to use table for layout its not good for search engin results too.