What is an escort warship?

Answer 1

An escort warship is a warship that sails along side unarmed or lightly armed merchant or military transports protecting them from threats.

An escort can be any warship assigned to guarding other ships but some have been purposely built for the task. Some example from the Second World War are Corvettes and Frigates which were designed to defend convoys from attacks by Submarines, Aircraft and Small Warships, Destroyer Escorts were more heavily armed with Torpedo's to destroyer Larger Warships threatening their convoys and even larger Escort Carriers carried entire aircraft squadrons for scouting and attacking threats. These ships were often cheaper and easier to produce than their front line compatriots of similar role with smaller hulls, less crew, armor, weapons and weaker engines only needing to keep up with slow merchant convoys and not intercept enemy war fleets.

Escorts differ from patrol warships which are independent from the ships they protect searching for potential threats and/or responding to ships in distress instead of guarding them.