BNB (Binance Coin) is a cryptocurrency that was initially created as an ERC-20 token on the Ethereum blockchain but later migrated to Binance Chain. BNB has several use cases within the Binance ecosystem, including trading fee discounts, token sales on Binance Launchpad, payment for goods and services, and more. Additionally, Binance Coin has seen significant adoption and utility within the crypto space, making it one of the top cryptocurrencies by market capitalization.