Passed by Congress in 2005, the REAL ID Act established minimum security standards for state-issued driver’s licenses and identification cards and prohibits federal agencies, like TSA, from accepting licenses and identification cards for official purposes from states that do not meet these standards.
Beginning January 22, 2018, driver’s licenses or state IDs issued by states that are not in compliance with the REAL ID Act and have not been granted an extension by DHS may not be used to fly within the U.S.
Beginning October 1, 2020, every traveler will need a REAL ID-compliant license or state ID or another acceptable form of identification to fly within the U.S.
You can check if your state is REAL ID compliant at dhs.gov/real-id-enforcement-brief. https://www.dhs.gov/real-id-enforcement-brief