Foil is fast game that employs the point to score a touch on the torso of the opponent.
Only hits to the torso score.
Hits not on the torso are considered off target and will not score but still stop the action.
If both fencers hit at the same time, the fencer with priority (called Right of Way, ROW) will be awarded the action (if the hit is on target, it will score, if it is off-target nothing will be done).
There are a couple technical considerations to executing a touch correctly
The tip of the foil must remain in contact with the target (the lame, or metallic vest the fencers are wearing) for 12 ms.: The point must plant firmly and directly on the target, any kind of swinging motion (like saber) will not depress the point correctly.
There is a 300 ms (1/3 of a sec) time delay for both fencers to score: A fencer with ROW still has 1/3 sec to finish a touch if the defending fencer is trying to hit first without defending. This may seem like a very short period of time, but it is an eternity on strip.