The word but is a coordination conjunction – one of the FANBOYS. Always use a comma before but when starting a second complete thought.
Today is sunny, but tomorrow it will rain.
I like milk, but my dad prefers soda.
Two complete thoughts. Insert a comma before but. Comma, but.
The word because is a subordinating conjunction. The word because always begins a subordinate clause.
If you begin a sentence with because, you will need a comma after the subordinate clause.
Because it is raining, the ballgame is postponed.
If you use the subordinate clause in the second half of the sentence, you do not use a comma.
The ballgame is postponed because it is raining.
Remember – comma before but. No comma before because.
▶It’s your turn. Does this sentence need a comma? If so, where should the comma be placed? I want to help but I do not have any time. Did you put a comma before but? Good for you!