A comma ( , ) is a punctuation mark used to separate words, phrases, or ideas in a sentence.
Commas are used to separate words or phrases in a series that has three or more items.
Example:
Allen and Lena ate eggs, bacon, and toast for breakfast.
I made my bed, picked up my books, and helped my mom fold the
towels.
Commas are used to separate parts of dates from each other. If a date is used in a sentence, commas can be used to separate the date from other parts of the sentence.