A NetID is your UW-Madison assigned username which provides access to University services, such as Office 365 email, MyUW, calendaring, student records, payroll information, etc. The NetID username is not case sensitive when used as a login credential. Your NetID username is randomly generated from University records and typically includes some combination of your first, middle, and last name. Your NetID username is not the same as your campus ID number or your email address.
Further information such as eligibility, activating, and changing your NetID username can be found here