Punctuation causes confusion for many, and consternation for us proofreaders. Full stops and commas are generally well understood. Other marks, however - the colon, semicolon and hyphen - are context-sensitive in use and are often misused. This article will explain and illustrate their proper use. 

Colon (:)  These are used after clauses that are complete sentences in themselves, in order to add additional information such as lists. 

There are three things with which a proofreader can help you: spelling, grammar and punctuation. 

Semicolon (;) These join two independent clauses in a sentence, making it clear that the two ideas are related. Use sparingly; it's all too common to use them where a comma would be more appropriate. 

Some writers use semicolons frequently; some tend to steer clear of them.

Hyphen (-): This mark joins words into compound words (e.g. mother-in-law). The same mark is called a dash when used in a different context - to include ideas that are not essential to understanding the sentence.

Many proofreaders - myself included - wish that knowledge of punctuation were more common.

If you still have any doubts or queries, feel free to contact me.