Below you will find the punctuation marks and their uses with examples.

Period-(.)

-end of declarative or imperative sentences.

Joe, put out the trash.  Today is a sunny day.

-abbreviations (addresses, names, initials, dates, time, metric measurement) 

-I live on 123rd St., Oct. 16, 2009, Dr. Smith is here., 2 gal. of milk. Dave M. Merryweather, 8:00 p.m.

Commas

-date (sept. 19, 2009)

-direct address (Stephanie, please come here.)

-words in a series (apples, pears, and peaches)

-geographic locations (Rome, Italy)

-appostitives (The flute, a woodwind instrument, creates a sweet sound,)

-before conjunctions (I went to the store, but I forgot to get the milk.)

-greeting to a letter (Dear Mom,)

-closing to a letter (love, )

-separate quotations ("I love milk," said Gabbi)

-names- (Jason M. Smoth, Jr)

Exclamation points (!) and question marks (?)

-end of an exclamtory sentence (That plate is hot!)

-express a strong emotion (No! I won't go!)

-end of an interrogative sentence (What time is it?)

Semicolons (;)

-separate the clauses of a compound sentence when they are not separated by a conjunction (and, but, or, nor, yet)

Ex: I have read many books, they are all interesting.

-items in a series when they are separated by commas.

I have lived in the following places--Westminster, Maryland; Pittsford, Vermont; Meriden, Connecticut; and Bel Air, Maryland.

Colon (:)

-after the saluation of a business letter.  (Dear Sir:)

-Before a list of items.  (You need the following books: Math, Science, Spanish, and LA)