A compound sentence is a sentence that connects two independent clauses, typically with a coordinating conjunction like "and" or "but". It is used to combine two or more sentences that are self-sufficient but related into a single, unified one. Compound sentences give writing a faster pace and unite related ideas, but they have a few more rules than standard sentences. To be a compound sentence, it needs at least two independent clauses that can each stand alone as a separate sentence. Compound sentences are easy to identify because they usually use a coordinating conjunction, which can be remembered with the acronym FANBOYS: for, and, nor, but, or, yet, and so. However, compound sentences can also use a semicolon to connect two clauses, in which case no conjunction is necessary.

Examples of compound sentences include:

• She closed the door and went to school
• I love my dog, and he is my best friend
• My job is very difficult, but I really enjoy going to work every day

Common problems with compound sentences include comma splices, where a comma alone is not enough to connect two sentences.