BNB stands for Binance Coin. It is the native cryptocurrency of the Binance cryptocurrency exchange, one of the largest and most popular cryptocurrency exchanges in the world. BNB has multiple use cases within the Binance ecosystem, including but not limited to:

1. Trading Fee Discounts: Binance users can use BNB to pay for trading fees on the platform, which provides them with discounts.

2. Token Sales: BNB is often used to participate in token sales and initial coin offerings (ICOs) launched on the Binance Launchpad.

3. DeFi and DApps: Binance Smart Chain (BSC), which is backed by BNB, has gained popularity for its compatibility with Ethereum and the ability to run decentralized applications (DApps) and DeFi protocols.

4. Staking: Binance users can stake BNB to earn rewards or participate in governance decisions on the Binance Smart Chain.

5. Cross-Chain Transfers: BNB can be used for cross-chain transfers and as a bridge asset between different blockchains.

Please note that the use cases and features of BNB may have evolved since my knowledge cutoff date in September 2021. Always check the latest information and developments regarding Binance Coin and the Binance ecosystem.