This online module focuses on the
use of commas [,] in formal writing. At school, you may have been
taught to use the comma in the following manner: "when you feel there
should be a pause" or "when in doubt, leave it out". These guidelines
are too vague and not very useful because people have very different feelings
about commas. Fortunately, there are more systematic, syntactic rules
for using commas (which can be applied without resorting to a variety of
In the Writer's Guide for Engineers textbook (pdf), study section 4.1 (pages 63-74) that focuses on the use of commas. After reading through the rules, go through the exercises 1-4.