It's a federal government initiative that standardizes ID requirements across states, usually requiring stricter paperwork to get one.

Honestly it's not the worst thing. For some reason there is no federal US ID card. (Besides a passport). Every state has their own and they all vary, before REALID they varied a lot more too... New Jersey used paper ID cards until like 2004.

It was created in response to the September 11th attacks. Before then, for constitutional reasons of Separation of Powers, most IDs in the US were issued by the states and they had varying standards of what was on the IDs, what criteria was required, and how they were issued. Some were easier to create fake versions of (mostly used by college students to buy alcohol), others were easier to obtain authentic IDs using fraudulent information. IIRC some of the hijackers used authentic IDs obtained fraudulently when they boarded their flights.

The Real ID Act of 2005 tried to standardize IDs nationally and the criteria for issuance, including verification of documents. It’s taken 20 years to get all of the states on-board and compliant, so they only started requiring passengers to present a Real ID recently, but there are a lot of people out there who haven’t obtained one yet based on when their state started issuing them and when they’ve had to renew their driver’s license. I think my state has offered Real IDs for a decade or more, but the Real ID was more expensive and optional for a while. I didn’t bother getting one until a couple years ago, partly because I already have a passport and that’s also a valid ID for flying.

Drivers licenses and other IDs are issued by the individual states, which can be issued by the states to anyone they decide to according to state laws. But the federal government (mostly just the TSA which is a part of the DHS) wanted to set a minimum standard for issuing IDs and so if you go through the process of proving you are who you say you are you get a state issued ID with a special star on it that indicates that the US government has 100% verified your identity.

Oh, and the DHS has just said that a real id is too unreliable to confirm your identity.

"REAL ID" is a new standard for ID the federal government implemented awhile ago. Before that, ID wasn't standardized between states.

It basically means you showed proof you were born in the US and gave the DMV your SSN.