Automated market maker (AMM)
Pooled liquidity that quotes prices algorithmically, added to the XRP Ledger by the XLS-30 amendment.
Liquidity providers deposit two assets into a pool and earn a share of trading fees, instead of managing individual orders.
On the XRP Ledger, AMM pools are quoted alongside order-book offers in the same path-finding step, so a trade can be filled from either.