Launched in September 2020, PancakeSwap is a decentralized exchange (DEX) running on Binance Smart Chain. Instead of allowing its users to trade ERC-20 and ERC-721 tokens, the DEX focuses exclusively on Binance Chain BEP20.
By using an automated market maker (AMM), the DEX allows tokens to be exchanged with no need for order books. This is quite similar to Uniswap's liquidy pools which are automated by smart contracts.