The first-ever tweet is up for sale, and it's expected to go for millions of dollars.         

Twitter CEO Jack Dorsey is selling the tweet as a "non-fungible token" which means it is unique, authentic, and verified.

The first tweet came out in 2006 with Dorsey writing "just setting up my Twitter."

The NFT comes with Dorsey's signature on Blockchain, a digital ledger used in crypto-currencies like Bitcoin.

So far, the top bid is $2.5 million from the CEO of Bridge Oracle.