The problem with "AND"

I have a problem. A very strange problem tonight it seems. I am consumed with the word "and." A long time ago in my Senior English class I remember my teacher telling us that to use and to begin a sentence was incorrect grammar.

However, I have seen and used to begin sentences in books for a long period of time. So tonight the word and has been my mission. Is it correct grammar to use this conjunction to start a sentence? Here is what I have discovered.

The conjunctions and, or, and but are primarily used to "conjoin" two interdependent clauses or phrases. This is the proper use of the conjunction.

Why do authors use this word to begin a sentence? I have also been taught not to begin a sentence with a prepositional phrase, but this has been done as well.

I believe my English teacher taught us this rule to eliminate run on sentences. Then I read where there is no hard fast rule that and cannot be used to begin a sentence. Primarily it is used in informal speech or writing, not proper writing.

Confused yet? I know I am. I suppose that to break a rule first you must understand the rule. I'm still working on understanding it.

So this is my thought for the night...
Now back to your regularly scheduled program...
Michelle