Here's a guide to help explain and correct punctuation:
1.The period is perhaps the easiest punctuation mark to master. It ends a sentence.
2.The question mark is used at the end of a direct question. Indirect questions take a period.
3.The comma is the punctuation mark most likely to cause angst. This is largely the result of the many different ways the comma is used.Sometimes, the comma indictes a pause that would occur if the sentence were spoken aloud. Other times, the comma seperates grammatical componetsf of the sentence. Finally, there are mechanical and stylistic uses of the comma that are simply conventional.
The presence or absence of a comma can change the meaning of a sentence --- sometimes dramatically. In extreme cases, an errous comma can make a sentence mean the exact opposite of what the writer intened. A careful writer must be a careful user of commas.
4.The semicolon is sometimes desed as stonger than a comma but weaker than a period. In certain uses, this is a reasonably accurate definition. Yet there is more to the semicolon than that.
Between independent clauses when a coordinating is ommitted. Most commonly, the semicolon is used between two independent clauses (i.e., clauses that could not stand alone as separate sentence)when a coordinating conjunction (for,and,nor,but,or yet,so) is omitted.
5.The colon has primarily three grammatical uses and several non-grammatical uses.
A.The colon is used to introduce a list of items.
B. Between independent clauses when the secondexplains or illustares the first.
C. Emphasis
Non-grammatical uses of the colon
A. Time
B. Ratio
C.Biblical references
D.Other references
E.Correspondence
6.The hyphen's primary function is the formation of certain compound terms.
7.The En dash is slightly wider than thehyphen but narrower