A semicolon is used between two complete thoughts.
Today is Tuesday; we have softball this evening.
Instead of the semicolon between the two complete thoughts, you can also use a comma and a coordinating conjunction (one of the FANBOYS).
Today is Tuesday, and we have softball tonight.
The semicolon and comma FANBOYS are interchangeable in sentences. Look at these examples:
I like pizza; Sam prefers hot dogs. – I like pizza, but Sam prefers hot dogs.
It is raining; softball is canceled. – It is raining, so softball is canceled.
The car broke down; I have to walk. – The car broke down, so I have to walk.
The sun is very hot; I am sweating. – The sun is very hot, and I am sweating.
Use a semicolon in place of a comma and one of the FANBOYS when you are joining two complete thoughts into one sentence.
▶It’s your turn. Use these two complete thoughts to make one sentence. Join the two complete thoughts with either a semicolon or a comma and one of the FANBOYS. I’m a dog person. Julie likes cats. That wasn’t so hard, was it?