Automated Market Making
The existence of AMM is something to primarily be credited to projects such as Bancor and UniSwap who brought it to market on the Ethereum Blockchain. AnySwap where FSN is primarily traded is the first protocol to truly have brought AMM cross-chain. AMM bases itself on the constant product market formula x*y = c.
After AnySwap was created; providing liquidity in LP-contracts became a large use case for FSN, since any crypto-asset can now be bridged onto Fusion and be paired with FSN in a liquidity pool. The same is of course true for native FRC20s like ANY or FUSE.