By Anna Malczyk
Here’s a quick-and-dirty rundown of everything you ever wanted to know about commas and semicolons!
The most important thing to learn first is the concept of an “independent clause”. Independent clauses are, very simply, complete sentences that can stand on their own. The opposite, dependent clauses, are those clauses that don’t form full sentences and have to be attached to an independent clause to exist. They are also often called subordinate clauses. Sometimes, two independent clauses can be linked together with conjunctions like “and” and “but” to make a longer sentence. For example:
Here we have two independent clauses linked with “and”. How can you tell? Just try separating them and see if you get two complete sentences: “I went to the park. It started raining.”
Here we have a dependent clause, “Even though I never met my cousin”. This is not a full sentence, and needs to be attached to one to make sense.
Why does all this matter?
Commas and semicolons can be used to separate two independent clauses. Commas can be used to separate independent and dependent clauses.
Commas
1. Use a comma when you want to separate two independent clauses that are joined with these conjunctions: and, but, for, or, nor, so, yet. 
2. Commas are also used to join a dependent clause to an independent clause.
Semicolons
1. Use a semicolon when two independent clauses are joined without any conjunctions. 
2. Semicolons are also used when the independent clauses are joined with these words: however, moreover, therefore, consequently, otherwise, nevertheless, thus.
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