Light ships are those ships which have low room for modules, but are small, agile and fast.
Light ships can only use M1 satellites.
Due to their low number of hitpoints, a single salvo of a heavy ship will often take them down. Extra plates, if they are not offset by inertial dampers or stabilizers, will slow down the ship too much, while speed is supposed to be the main asset of light ships.
Therefore, for survivability, light ships often capitalize on speed, agility and the pilot's skills to evade enemy fire.