Horde

Overview
A group of infected acting towards the same stimulus is known as a horde. Hordes are generally one of two sorts: walker hordes and runner hordes. In this regard, hordes are usually only comprised of common infected. Hordes can prove a deadly obstacle in many situations, and with them come new rules in dealing with the massed infected.

Background
Hordes are either spawned (most often for scripted encounters and events) or they are formed by individual infected collecting in a group. Once this group has grown to a significant number, they will have formed a horde and their behavior radically changes.

A horde can form instantaneously. Noisy areas are more prone to collecting infected and forming hordes.