Hinders enemy advancement.
Barriers are the most basic defense and also the cheapest at first. It stops the enemy from advancing and it changes visually from level 1 (being made out of wood) and level 10 (being made out of metal). Walls are recommended to just surround important buildings such as: command center, defenses and resource buildings. The best troop for destroying this defense are Special Ops with just requiring 2 of them in average (depending of the level). Other troops which are not Special Ops would have more difficulties in destroying walls.