The Period / Full Stop

The period is perhaps one of the more humble of grammar items despite the fact that it is probably the most widely used. 

According to tradition, Aristotle said that a period was that "portion of a speech that has in itself a beginning and an end." So the use of periods have been around since the ancients.

Though its origins are not exactly clear, much of Chaucer's writings had a full stop, or period, at the end of each line without much reference to other syntax in general. 

Typically, the period is used in three, ok maybe four, distinct ways making it perhaps the easiest punctuation item to learn and use.

We use a period at the end of a command or statement.

"Remember, you must hand in your projects on Monday morning."

I think I'll go to the store after lunch. 

We use a period with abbreviations.

Mr. Jones lives in Washington D.C. and returns from work in the p.m.. 

Some short forms, such as TV and UN are not abbreviations. We pronounce them as they are written and they are not followed by periods.

We use a period at the end of an indirect question.

The driver wanted to know why the car kept stalling. 

My mother used to wonder why I never cleaned my room. 

We use a period to separate two parts of a decimal.

Pi is usually said to be 3.14 (prononced three point one four)