The front kick is common to almost every Martial Art and more than likely the first one new students learn.
In Taekwondo the front kick has several variations. In Korean, it is referred to as Ap Chagi (Ap - front, Chagi - kick). The variations in how a front kick is delivered differ in which part of the foot is used to strike the target, and in how the leg is moved. Front Kick is rarely used in competition because the risk of accidentally striking your opponents groin and getting penalized for it is quite high. Front kick (particularly jumping front kick) is popular for breaking techniques.
The classic Taekwondo front kick uses the ball of the foot as the weapon. You have to pull back your toes to avoid injuring them. Try to raise the knee of the kicking leg slightly higher mid kick than it's finishing height to get extra "push" into the kick. The force is directly forward and to achieve maximum power the hips are thrust forwards slightly just as the kick is completed. Make sure you don't lean back to far and keep your guard up.
Another variation is the Push Kick. Instead of striking with the ball of the foot, the entire base of the foot is used to push an opponent away. The kicking knee needs to come as high as possible for a push kick to have enough power to move the opponent.