The period or full-stop is a punctuation mark which is represented by a point (.) This tag does not discuss time.
The period (often called a full stop) can be used to end a sentence, end an abbreviation (as in etc. or J. Atwood), or, in American English, end a title (Ms.).
For more information on the usages of periods, see the Wikipedia page Full Stop.
Note that this tag refers to a particular punctuation mark. It does not refer to periods of time.