OpenSea is a decentralized marketplace for buying and selling digital assets, such as non-fungible tokens (NFTs), on the Ethereum blockchain. The platform allows users to discover, buy, and sell unique digital assets, including collectibles, art, in-game items, and more. OpenSea offers a wide range of features and tools for users, including the ability to list and sell assets, create and manage auctions, and track and manage assets using an integrated wallet. OpenSea is built on top of the Ethereum blockchain, which provides a secure and transparent platform for buying and selling digital assets.