College Green is a Herring Bank Student Checking account where your school can Direct Deposit any money they owe you. That means it automatically shows up in your account instead of waiting for a check.
It's also a debit MasterCard that doubles as your student ID, and you can use it anywhere you see the MasterCard logo.
Each school uses the College Green program in its own way. So your student ID is not just a debit card; it may be used as a library card or for access to dorms, cafeterias and events.