Why should I use a container div in HTML?

Question

I have noticed a common technique is to place a generic container div in the root of the body tag:

  
    ...
  
  <         


        

Answer 1

The most common reasons for me are so that:

1. The layout can have a fixed width (yes, I know, I do a lot of work for designers who love fixed widths), and
2. So the layout can be centered by applying text-align: center to the body and then margin: auto to the left and right of the container div.