A clause is a group of related words containing a subject and a verb (as opposed to a phrase, which does not contain a subject-verb relationship, such as "in the morning" or "running down the street" or "having grown used to this harrassment").

Independent Clauses can stand by themselves as separate sentences, as in "Bob didn't mean to do it, but he did it anyway." (two independent clauses, connected by a comma + a little conjunction)

Dependent Clauses cannot stand by themselves and make good sense. They must be combined with an independent clause. There are several kinds of dependent clauses, categorized according to their function in the sentence:

• Adverb clauses provide information about what is going on in the main (independent) clause: where, when, or why. "When the movie is over, we'll go downtown." or "John wanted to write a book because he had so much to say about the subject."
• Adjective clauses work like multi-word adjectives. "My brother, who is an engineer, figured it out for me." or "The bridge that collapsed in the winter storm will cost millions to replace."
• Noun clauses can do anything that nouns can do. "What he knows [subject] is no concern of mine." or "Do you know what he knows [object]?" or "What can you tell me about what he has done this year [object of the preposition "about"]?"