A compound sentence is made up of two simple sentences – two complete thoughts.
Those two thoughts are joined by a comma and a conjunction.
There are seven conjunctions in the English language: for, and, nor, but, or, yet, so. Notice that the first letter of each of these seven conjunctions, when written in a row, make the word FANBOYS.
When writing a compound sentence, we say we are joining the two simple sentences with a comma FANBOYS.
Look at these examples:
Simple sentence: I have a dog.
Simple sentence: Susan has a cat.
Compound sentence: I have a dog, but Susan has a cat. We use a comma FANBOYS to make the compound sentence.
Compound sentences can sometimes use different conjunctions. Look at this sentence:
I have a dog, and Susan has a cat.
Using the conjunction and instead of but gives a slightly different meaning to the sentence, but both words work.
When joining two simple sentences into a compound sentence, always place a comma before the conjunction.
It’s your turn. Place a comma in this sentence: Today is sunny but tomorrow will be rainy. Did you figure it out? Good for you!