OpenSea is the first and largest peer-to-peer marketplace for cryptogoods (like an eBay for crypto assets), which include collectibles, gaming items, and other virtual goods backed by a blockchain.
On OpenSea, anyone can buy or sell these items through a smart contract. The OpenSea team has backgrounds from Stanford, Palantir, and Google, and is funded by YCombinator, Founders Fund, Coinbase Ventures, 1Confirmation, and Blockchain Capital.