Commas between Main Clauses

Use a comma between two main clauses which are separated by and or but.

Example: We ran out of fuel, and the nearest petrol station was 5 miles away.

Use a comma to separate parts of a sentences in a sequence.

Example: She ran down the stairs, opened the door, saw her boyfriend(,) and gave him a kiss.

Don’t use a comma if these parts of the sentence are separated by and or but.

Example: She ran down the stairs and opened the door and saw her boyfriend and gave him a kiss.

Note: Don’t use a comma, but a semi colon, if two main clauses are not separated by and or but.