PUNCTUATION TIPS - THE APPROPRIATE USE OF COMMA.

A comma [,].

Is used or to:

Separate words in a list, but you must sometimes omit them before "and."

Example - I bought a red, pink, and white roses tea, coffee, milk or hot chocolate.

Separate phrases or clauses.

Example - If you keep calm, take your time, concentrate and think ahead, then you're likely to pass your   test.