A simple sentence is built from the minimum of a subject and a main verb. It can be very short in length (but doesn't have to be): 'The angry dog barks.' It puts across one simple idea: 'Rebecca sang.

Letters represent sounds. Words are built from letters. A group of words makes a phrase. Add a subject and verb, and you have a clause. If that clause expresses a complete thought, we call it a ...

Here's my favorite sentence: "Aren't I?" In recent months, I've trotted it out half a dozen times to end an argument about grammar. It works. Better than any other sentence I know, "Aren't I?" ...