A smart order router (SOR) is an automated process used in online trading that follows a set of rules when looking for trading liquidity. The goal of an SOR is to find the best way of executing a trade.
Most major institutional investors and brokers will use a smart order router in order to find the best possible prices for trades as quickly as possible. Each smart order router will be set up according to different needs.
Smart order routers are often deployed as part of an automated trading system, though the level of automation involved varies between routers.