English — Reason: because / as / since / so
To give a reason, use because, as or since before a clause: I stayed home because it was raining. To give a result, use so: It was raining, so I stayed home.
How it works
because, as and since introduce the reason and are followed by a full clause (subject + verb): We went inside because it was cold. because of is followed by a noun, not a clause: We went inside because of the cold. so introduces the result and always stands between the two clauses: It was cold, so we went inside.
Examples
| Example | Function |
|---|---|
| I was late because the bus broke down. | because + clause — reason (mid-sentence, no comma) |
| Because the bus broke down, I was late. | because clause first — comma after it |
| As it was getting dark, we headed home. | as — reason (formal, known info) |
| Since you're here, let's start. | since — reason (already-known fact) |
| The match was cancelled because of the rain. | because of + noun — reason without a clause |
| It was raining, so we took a taxi. | so — result (comma before so) |
Good to know
Don't confuse because and because of: because is followed by a clause (because it was cold), while because of is followed by a noun (because of the cold). Also, use because to answer a Why? question, not so — so states the result, not the reason: Why did you leave? — Because I was tired. (not so I was tired).