when do you see a comma in a sentence

A comma is typically used in a sentence to separate components such as clauses, phrases, or items in a list. Here are some common instances where a comma is used:

1. To separate items in a list: "I bought apples, oranges, and bananas."
2. To separate two independent clauses when connected by a coordinating conjunction: "She wanted to go to the party, but she had to work."
3. To separate introductory elements from the main part of a sentence: "After finishing his homework, Jack went out to play."
4. To separate nonessential information or phrases from the main part of a sentence: "John's dog, a golden retriever, is very friendly."
5. To separate main clauses if they are not connected by a coordinating conjunction: "He ran to catch the bus, she walked."

These are just a few examples, and there are other cases where commas are used in sentence structure. Proper comma usage depends on the specific structural rules and style guidelines.