What document can prove only an employee's identity?

A driver's license serves as a valid form of identification that proves an individual's identity, as it typically includes a photo, full name, address, date of birth, and other identifying information. This makes it a key document for establishing identity, especially in contexts such as employment verification or when applying for other services.

While a U.S. passport also proves identity and may sometimes be used in similar contexts, it is more comprehensive as it also provides proof of citizenship. A birth certificate is primarily a record of birth and while it can help establish identity, it does not include a photo or other verification elements like a driver's license does. A Social Security card primarily serves to verify one's Social Security number and isn’t intended as a photo ID, so it does not function as proof of identity in the same context as a driver's license.