Period
The end of a complete sentence should be marked by a period, a question mark, or an exclamation point. If a sentence is not complete and it is terminated by a period, we have a sentence fragment as in the sentence below.
Incorrect: | You can use any resources. To complete your take-home exam. |
Correcting the Problem
Correct: | You can use any resources to complete your take-home exam. |
Rule to Remember
The end of a complete sentence should be marked by a period, a question mark, or an exclamation point.
Sentence fragments are discussed in a different section of this tutorial. This section will explore the uses of punctuation marks used to mark the end of sentences.
End of Sentence
A period is used to signal the end of a complete sentence.
Correct: | This is the best paper I've ever written. |
A period is also used at the end of an indirect question.
Correct: | The teacher asked us if we understood the assignment. |
Polite requests can be followed either by a period or by a question mark.
Correct: | Will you please mail this letter for me. |
Correct: | Will you please mail this letter for me? |
Abbreviations
A period should be placed after every part of the abbreviation:
A.D. | Dr. Watson |
a.m. (am is also possible) | Ave. |
Very common abbreviations and units of measure don't take periods:
mph | mp3 |
rpm | mpg |
Academic degrees can be written with or without periods:
DDS | EdD |
M.S. | B.A. |
Lower case abbreviations are usually written with periods: i.e.
Government agencies and international organizations are written without periods:
FBI | UNESCO |
UN | NATO |
UNICEF | EU |
Question Mark
Direct questions are followed by a question mark.
Correct: | The teacher asked, "Do you understand the assignment?" |
Exclamation Point
Exclamatory sentences should be followed by an exclamation point.
Correct: | Wow! That's incredible! |