(NEXSTAR) – In the latest non-fungible token (NFT) auction to fetch millions of dollars, Twitter and Square CEO Jack Dorsey sold his first tweet ever for millions of dollars Monday.

Fifteen years after tweeting “just setting up my twttr,” Dorsey sold an NFT of the five-word message for more than $2.9 million through the platform Valuables by Cent.

The bidding history showed a two-person battle at the end between tech entrepreneur Justin Sun and Sina Estavi, the CEO of Bridge Oracle, which sent the price from $500,000 up to its final sale amount.

Dorsey thanked Estavi Monday, tweeting that all proceeds would go to his Give Directly Africa response fund.

It’s just the latest auction of an NFT to make headlines with eye-popping bids.

Earlier this month, Christie’s said it auctioned off a digital collage by an artist named Beeple for nearly $70 million, in an unprecedented sale of a digital artwork that fetched more money than physical works by many better known artists.

The piece, titled “Everydays: The First 5,000 Days,” sold for $69.4 million in an online auction, “positioning him among the top three most valuable living artists,” Christie’s said via Twitter on Thursday.

Christie’s said it also marks the first time a major auction house has offered a digital-only artwork with a non-fungible token as a guarantee of its authenticity, as well as the first time cryptocurrency has been used to pay for an artwork at auction.

In economics jargon, a fungible token is an asset that can be exchanged on a one-for-one basis. Think of dollars or bitcoins — each one has the exact same value and can be traded freely. A non-fungible object, by contrast, has its own distinct value, like an old house or a classic car.

Cross this notion with cryptocurrency technology known as the blockchain and you get NFTs. These are effectively digital certificates of authenticity that can be attached to digital art or, well, pretty much anything else that comes in digital form — audio files, video clips, animated stickers, this article you’re reading.

NFTs confirm an item’s ownership by recording the details on a digital ledger known as a blockchain, which is public and stored on computers across the internet, making it effectively impossible to lose or destroy.

At the moment, these tokens are white-hot in the collecting world, where they’re being used to solve a problem central to digital collectibles: how to claim ownership of something that can be easily and endlessly duplicated.

The Associated Press contributed to this report.