1. Use a comma between the day of the week and the month-date.
I will be there on Monday, December 25.
2. Use a comma to separate two or more items in a sentence.
I love boxing, my family and my dog.
3. Use a comma between the name of a city and the state.
I was born in Woodbridge, Suffolk.
4. Use a comma after introductory words like yes / no / wow / hey.
Wow, we won the match!
5. Use a comma to separate the name of a person in a direct address.
Harry, what happened to you? / What happened to you, Harry?