Worldcoin says this is just the beginning, and is in the middle of a world tour to add more eyeball scans to the more than 2 million already collected. And no, this is not a sci-fi movie. The company is really doing this as part of an ambitious project it says will preserve our “humanness” as artificial intelligence takes over more of the world.

So what exactly is this all about? And, perhaps more important, should you think about signing up?

What is the orb, and what does it do?

The orb is shiny and about the size of a large grapefruit, and was built with the help of a top Apple designer. Worldcoin has made around 1,500 of the devices and is building more. You can see a picture of one above.

The orb has one purpose: to scan and record your iris. It then converts the biometric image into an impenetrable string of numbers, which Worldcoin refers to as an IrisCode. When combined with an algorithm, the code verifies you’re a unique human, and confirms that via an app on your phone.

Fortune‘s Leo Schwartz agreed to a scan in March—read his feature if you want the full technical explanation.

How do I sign up?

Worldcoin is offering the orb service in 35 cities around the world, including Miami and New York. The company is also all in the middle of a tour that will bring the device to a series of pop-up sites. You can find a list of locations on Worldcoin’s website.

What’s the point?

Worldcoin is owned by a parent company called Tools for Humanity that wants to bring blockchain-based digital identity tools to everyone. The premise is that, in a world dominated by bots and artificial intelligence, it will become hard to tell who’s real and who’s a machine.

The best solution, the company claims, is to for you to use the unique image of your iris as a foolproof way to prove your “humanness.”

Who is behind this?

The Worldcoin orb is the pet project of Sam Altman, a Stanford dropout and entrepreneur who for years ran the prestigious Silicon Valley incubator Y Combinator. Right now, Altman is best known as the founder and CEO of OpenAI, the company that developed the popular A.I. tool ChatGPT.

Worldcoin has raised well over $200 million from venture capital funds like Khosla Ventures and Bain Capital.

What’s the crypto angle?

Those who agree to get their iris scanned receive a small number of cryptocurrency tokens known as Worldcoin, or WLD. The tokens began trading this week and are currently worth a little over $2 each.

Worldcoin distributed the tokens by means of an “airdrop,” which means sending them directly to the wallets of eligible recipients rather than listing them on an exchange. Users in the U.S. were not eligible to receive the airdrop due to regulatory concerns, but that could change.

Further down the road, Worldcoin envisions a world where the tokens are part of a larger ecosystem in which a wide variety of services verify identities with iris scans. The company also believes it could become part of a futuristic universal basic income scheme.

Should I sign up? Is it safe?

That’s up to you. Worldcoin claims the orb is designed so no one—not even the company itself—is able to identify you thanks to an advanced privacy technology called zero-knowledge proofs.

While this technology is considered effective by privacy experts, critics have warned it’s dangerous to give your biometric data to a private company, and some say they don’t trust Worldcoin to act responsibly.