CSS3 introduces the multicolumn layout module: It lets you divide a single element (like a div full of text) into a three, four, or more columns. It provides CSS properties to determine the number of columns, the space between columns, and to add a line (a rule) between the columns.
Imagine reading a newspaper and having the body copy extend across the entire page width. It would be easy to lose the line you were on, wouldn’t it? There is a reason newspapers break text into columns of text—it’s easier to read! Web pages are the same; a paragraph of text that stretches margin to margin of the full width of a browser window is harder to read than one that is confined to a narrower area.
With CSS3 columns, the browser determines when to end one column and begin the next without requiring any extra markup. You retain the flexibility to change the number of columns as well as their width, without having to go back in and alter the page’s markup.