Clause: A grammatical unit that contains both a subject and a verb. An independent, or main, clause expresses a complete thought and can stand alone as one sentence. A dependent, or subordinate, clause cannot stand alone as a sentence and must be accompanied by and independent clause.


Examples:

Lazy students whine.
students=subject | whine= verb

Pepsi spilled over the glass and splashed onto the counter.
Pepsi= subject | spilled, splashed= verbs

My dog loves pizza crusts.
dog= subject | loves= verb




Independent Clause:

An independent clause is a group of words that contains a subject and verb and expresses a complete thought. An independent clause is a sentence.

Example: Jim studied in the Sweet Shop for his chemistry quiz.


Dependent Clause:

A dependent clause is a group of words that contains a subject and verb but does not express a complete thought. A dependent clause cannot be a sentence. Often a dependent clause is marked by a dependent marker word.

Example: When Jim studied in the Sweet Shop for his chemistry quiz .


http://www.chompchomp.com/terms/clause.htm

http://owl.english.purdue.edu/handouts/grammar/g_clause.html