This is the best book on punctuation that I know. Each punctuation mark is very well explained. However, to be brief, I will comment only on how professor Trask explains the use of the comma. He says that there are only four uses of the comma. He lists the four uses of the comma and presents a test designed to help you to decide for yourself if a comma is used properly or not. Sometimes it is hard to apply the test. For example consider the following sentence that you can find on page 39 of the book. "The situation is clear: if you have unprotected sex with a stranger, you risk AIDS." Now try to apply professor Trask test to decide if the comma in this sentence is correct or not. I have tried the test in other examples and found it very easy to use. This should be compared with the, also excellent, approach by professor Anne Stilman in the book "Grammatically correct". She lists six rules on how to use the comma each rule with several sub cases. I personally prefer professor Trask approach. The approach to the comma example is the same to the other punctuation marks. Every one of them is carefully explained in probably the most possible concise away

Dr Trask combines readabilty with rigor in a virtuoso treatise. Buy it!

Picked up Trask's Penguin Guide to Punctuation in Oxford UK this July, read it on the flight home and am already using it for executive English improvement classes.

It's neat because it's not pretentious and strips away most of the historically rigid and stern grammar and punctuation 'rules'of the last 50 years. The author wants to make punctuation a 'living' art, and clear communication and sense of meaning are more important than abiding by old disciplines. He uses plently of sample phrases and sentences to illustrate 'correct'usage and highlights definite 'no nos'.

Differences between American and British punctuation are covered, but rather superficially. In its 180 pages there is enough to keep you on the right track.