The =COUNTIF formula takes data from a sheet (Form Responses) and begins to count how many times it appears.
This formula is useful if you are counting how many times someone has signed up for a project, counting votes or even using to filter answers on a Google Form.
I use this formula a lot to make sign-up sheets for activities where students are to bring a specific number of items. By using another formula (CLICK HERE TO LEARN MORE) and an add-on for Google Forms (CLICK HERE) I can restrict how many students sign up for a particular item.