Periods are most commonly found at the end of
sentences. However, they have other uses. Periods can
be used in the following ways:

Signal the End of a Complete Sentence

The dog runs fast.
The boys studied mathematics.

Initials

J.P. Franklin
I.M. Pei

Abbreviations and Acronyms

Y.M.C.A.
U.S.A.
P.E.T.A.
Dr.
Mr.
Mrs.

Periods