They’re un­usual in word-proces­sor lay­outs, but I don’t ob­ject to columns in a long doc­u­ment. Columns are an easy way to get a shorter and more leg­i­ble line length with­out us­ing large page mar­gins. On a stan­dard 8.5″ × 11″ page, two or three columns are fine. Four is too many.

Usu­ally columns look neat­est when the rows of text are aligned ver­ti­cally be­tween columns (i.e., as if they were sit­ting on the same base­line). Look at a de­cent news­pa­per for an ex­am­ple. Get­ting this re­sult takes a lit­tle ex­tra ef­fort. Note your line spac­ing and make sure any space be­tween para­graphs works out to a whole mul­ti­ple of the line spac­ing. The two most com­mon op­tions: set space be­tween para­graphs to zero, or set it to be the same as the line spacing.

On the web, though most of to­day’s web browsers sup­port CSS-based columns, as a de­sign tool they’re not that use­ful. Prac­ti­cally speak­ing, columns need to fit in­side a fixed ver­ti­cal space. But by its na­ture, a web page has an in­def­i­nite bot­tom edge. Still, columns can be use­ful in sit­u­a­tions where you have a small amount of text or a list of links that can fit on a browser sin­gle screen. See sys­tem fonts for an ex­am­ple of this technique.