Semicolons are used in place of a period, or a comma and a conjunction, to connect two related sentences. Watch out!: a common error is to treat "however" as a coordinating conjunction such as "but," but this is incorrect. Use a semicolon before "however" if combining independent clauses: I was going to mail the letter; however, I forgot. (Semicolons can also be used to separate complicated lists; however, this is generally not tested on the ACT.)
Example: I am addicted to pudding; I have a pudding cup on average three times a day.