A tank is an armoured combat vehicle, typically armed with a large cannon mounted on a turret and a few machine guns.
A tank is covered in thick armour to protect it from enemy weapons. Tanks have tracks that wrap around its wheels to spread out its weight and let it cross rough ground. Most tanks have a powerful gun and one or more machine guns.
A tank's crew is normally 3-5. A driver, commander and gunner are always present. There may also be a loader, who handles the ammunition for the main gun (so the gunner doesn't have to take eyes off the target). Some WWII tanks also had a separate soldier responsible for the radio.