Punctuation marks are the symbols used in writing. They act like the traffic signs in writing. They tell us when to stop, slow down, or even when to pay attention to something. They make reading easier and writing better. It's important to be able to recognize punctuation marks and know how each one works.
The Period serves as a stop sign and tells us where a sentence ends and where the next one begins. It signals the end of declarative sentences (sentences which state facts or opinions) and commands that do not express great urgency. A period marks the end of a complete thought. Periods are also used in abbreviations of words, such as in Co. (company), St. (street), or U.S.A. (United States of America).
Rules for using the Period
Rule 1: Use a period at the end of a statement.
It is sunny and warm outside today.
("Today" is the last word of the statement - use a period)
I will take the dog for a walk.
("Walk" is the last word of the statement - use a period)
Bob runs very quickly.
("Quickly" is the last word of the statement - use a period)
Rule 2: Use a period in an abbreviation.
I went to visit Washington, D.C.
("D.C." is the abbreviation for District of Columbia - use a period)
She lives on Oak St. in Baltimore.
("St." is the abbreviation for street - use a period.)
My father worked for the Water Co. for many years.
("Co." is the abbreviation for company - use a period)
Rule 3: Use a period in an abbreviation.
Jane asked me why we left early. (Use a period for a sentence that describes a question but does not ask one.)
She asked what we had for homework. (Use a period for a sentence that describes a question but does not ask one.)
Sam asked why I didn't understand the story. (Use a period for a sentence that describes a question but does not ask one.)
Rule 4: Do not end a sentence with a period if the last word in the sentence ends with the period.
Harry lives in the U.S.A. ("U.S.A." ends with a period, so you don't add one to the end of the sentence.)
I have an appointment with Anna Smith, M.D. ("M.D." ends with a period, so you don't add one to the end of the sentence.)
The handy chart below can help you remember the rules and uses of the period.
Use at the end of statements and indirect questions.
Use in abbreviations.
Used at the end of an indirect question, which describes a question, but does not ask one.
Do not use if the last word in a sentence ends with an abbreviation.