Microsoft® Manual of Style, Fourth Edition

Commas

Comma usage is governed by both convention and grammar. For more details about comma usage, see Harbrace College Handbook.

When to use commas

In a series consisting of three or more elements, separate each element with a comma.

Microsoft style

You need a hard disk, a VGA monitor, and a mouse.

Not Microsoft style

You need a hard disk, an EGA or VGA monitor and a mouse.

Use a comma following an introductory phrase.

Microsoft style

In Windows, you can run many programs.

Not Microsoft style

In Windows you can run many programs.

If you specify a full date in midsentence, use a comma on each side of the year.

Microsoft style

The February 4, 2003, issue of the New York Times reported that .…

Not Microsoft style

The February 4, 2003 issue of the New York Times ...