The Execute Command

The /execute command is a useful command used in many situations.

Overview
The /execute command basically activates a command at a coordinate in relation to certain entity.

Syntax
/execute   

Explanation
The entity value is the entity mentioned in the overview. The x, y, and z values are the coordinates of the activated command. If they are just values, like 132, 45, and 1367, the entity value won't matter. However, if you want to do something to the block under someone, you can use tildas (~) to specify that. The command value is the command ran at that spot.

Trivia

 * Can be used to make "Midas Touch" kind of mods.
 * Probably the most used command in minigames.