A sally port is often defined as a fortified entrance or exit from a military structure or fortress. Other synonymous terms include "postern gate," "secret door," and "drawbridge." These terms are used to describe entrances or exits that are kept hidden or protected to provide an added layer of security in the event of an attack or siege. Other terms that are sometimes used interchangeably with sally port include "gatehouse," "portcullis," and "rampart entrance." Each of these terms refers to a specific type of fortified entrance, but all describe structures designed with the same goal in mind: to provide a secure and protected way in or out of a fortified structure.