Light infantry is a designation applied to certain types of foot soldiers (infantry) throughout history, typically having lighter equipment or armament or a more mobile or fluid function than other types of infantry, such as heavy infantry or line infantry. Historically, light infantry often fought as scouts, raiders and skirmishers—soldiers who fight in a loose formation ahead of the main army to harass, delay, disrupt supply lines, and generally "soften up" an enemy before the main battle. After World War II, the term "light infantry" evolved, and now generally refers to rapid-deployment units (including commandos and airborne units) that specifically emphasize speed and mobility over armor and firepower.