The comma is used for several reasons in English

  • To separate items in a list
    • e.g. I went shopping and bought apples, bananas, oranges and grapes.
  • To separate extra information from the rest of the sentence
    • e.g. My cat, which has lost its tail, disappeared up grandma's chimney.
  • To separate clauses in compound sentences in order to make them easier to read
    • e.g. Amy was usually very good at going to the shop before school, but her alarm didn't go off this morning.
  • To elimate ambiguity in the meaning of what you've written so that the reader isn't left confused

Commas to avoid ambiguity of meaning: