Use a comma when two independent clauses are joined by a conjunction.
Grammar can be difficult to understand, but it is necessary for effective writing.
A comma is used after an introductory phrase or dependent clause.
To get a good grade, you must hand in all your assignments.
After graduation, your job search can begin.
Commas are used to separate items in a series or list.
To make bread you need flour, yeast, sugar, salt, and water.
Use a comma between multiple adjectives.
The sturdy,lightweight backpack was an excellent gift.
A comma is used after transitional words such as however, for example, moreover, etc.
For example, many students have difficulty constructing thesis statements.
However, a well-supported thesis almost always ensures a good grade.
Comma splices occur when two independent clauses (which could stand as separate sentences) are joined by a comma only.
Two independent clauses as separate sentences:
Comma splices are a significant grammatical error. I should avoid them.
Incorrectly joining two independent clauses with only a comma (a comma splice):
Comma splices are a significant grammatical error, I should avoid them.
Correctly joining two independent clauses (avoiding comma splices):
1. Using a comma + a coordinating conjunction (and, but, or, nor, for, so, yet)
Comma splices are a significant grammatical error, so I should avoid them.
2. Using a semi-colon
Comma splices are a significant grammatical error; I should avoid them.
Use a semicolon to join two independent clauses when they are closely linked together.
I went to the grocery store; milk was on sale.
Use a semicolon to join two independent clauses with a conjunctive adverb, or another transition.
I went to the grocery store to buy milk; however, the sale ended yesterday.