Semicolons are a little tricky–they are used mainly to join two independent clauses (i.e., two simple sentences) together to show that the first relates very closely to the second. They are sometimes used in long lists for clarity. This site gives a lot of examples and variations on when to use a semicolon. For a few more examples, see here.
Tip: Never use a semicolon in the place of a comma or a colon (:). If you’re unsure even after going through the examples above, use the comma–a simple but grammatically-correct sentence is always fine!
Posted in: Grammar