Congress passed the REAL ID Act in 2005. The act established minimum security standards for state-issued driver licenses and ID cards. Starting October 1, 2020 anyone wishing to board an airplane or access certain federal facilities will be required to present a REAL ID compliant license or ID card.
REAL ID is a law, not an actual piece of ID. Per the law, there are many pieces of existing identification options that will work including:
See the full list of ID documents accepted for air travel.