“Question,” wrote CNN anchor Sara Sidner in an X post on Thursday. “Where did this blue check suddenly come from?”

It’s all thanks to a policy change Musk announced last month, but its impact was delayed: Many eligible accounts were only notified that they would be verified this week.

Here’s what you should know.

Who is getting a blue check?

All kinds of folks. Popular YouTubers, content creators, industry analysts, artists, journalists, researchers, Luke Skywalker and many other accounts with large followings have reported being granted a complimentary blue check in the last few days.

But even if you already have a big audience on X, you shouldn’t expect to be given a verified blue check unless a significant portion of your followers are paying X customers.

In late March, Musk said on X that, going forward, all accounts with over 2,500 verified subscriber followers would get “Premium features” — including that blue check — for free. Accounts with more than 5,000 verified followed, meanwhile, would get access to X’s Premium Plus features, which among other things include ad-free X use.

Since then, neither Musk nor the company’s spokespeople have commented to clarify those criteria. But from what we can tell, the key words here are “verified subscriber” — that refers to X users who already pay at least $8 per month for the platform’s Premium service. (Unfortunately, the platform doesn’t offer a count of one’s verified followers, so checking for yourself can be tricky.)

What’s less clear is whether accounts with gold check marks (granted to official organizations on the platform) or gray check marks (which denote government organizations and officials) contribute to that count.

For one, X reserves the right to cancel those free Premium subscriptions at its sole discretion. In other words: X giveth, and X can taketh away.

X’s blue checks also don’t quite mean what they used to; before, they were signifiers of a person’s authenticity and notability.

That’s not to say everyone is upset to see them. Erin Brockovich — yes, that Erin Brockovich — said in a post Thursday that she finds the free blue check “oddly satisfying,” if only because it means the company on some level “caved.”

As a result, some high-profile X users who have recently been verified have sought to put some distance between themselves and the new blue checks they’ve been unilaterally granted.

Mark Hamill, best known for playing Star Wars’ Luke Skywalker, asked his followers on Wednesday not to judge him for sporting a complimentary blue check mark.

Timnit Gebru, the AI ethicist who serves as the executive director of the Distributed AI Research Institute, told The Washington Post that she hid the blue check to avoid the appearance of endorsing “anything” Musk is doing. Eva Galperin, director of cybersecurity for the Electronic Frontier Foundation, hid her blue check for similar reasons.

“It is not possible to opt out of Premium, but at least I can make sure that no one mistakes me for a person who would give this place money,” she said in a post on X.

The company did not respond to a request for comment on the reasons behind the move, but there are a few possibilities worth pointing out here.

First is the idea that X wants to use this new wave of popular, freshly verified accounts to heighten the prestige of being verified.

Karen North, a professor of digital social media at the University of Southern California’s Annenberg School for Communication and Journalism, told The Post that “in a world where the celebrities and public figures refuse to pay for the check mark, then the verification loses its value.”

With that in mind, X’s move could sweeten the idea of a monthly fee to people who would like to be viewed as equivalent to some of X’s highest-profile users.

Some on X speculated that this policy shift is intended to counter a technique known as “blue blocking,” where people use browser extensions to automatically block verified X accounts.

By verifying a large number of popular accounts with no clear way to opt-out, users can’t rely on this tactic to clean up their feeds without potentially blocking people they actually want to hear from.