RAY is the native token of Raydium, an Automated Market Maker (AMM) built on the Solana blockchain. RAY will let token-holders stake RAY to generate additional yields and participate in a limited governance model to let RAY holders vote on community proposals and amendments. Raydium leverages access to a Serum’s decentralized order book to facilitate fast trading and deep liquidity across Raydium’s liquidity pools and Serum’s order books. By connecting the AMM to an order book and allowing Raydium to directly submit orders onto Serum’s order book and vice versa, the entire Solana ecosystem benefits as liquidity across both protocols is aggregated. Raydium can help users get the best prices when swapping tokens through its best price swap feature, which determines whether swapping within a liquidity pool or through Serum’s order book will provide the best price. 

More information here https://raydium.io/