Rule

Rule may mean:

Norm
- Law
- Morality
- Monastic rule, the basis upon which a monastic order is run.
Theorem, in mathematics, something which is always true.
Mathematics, a determinate method for performing a mathematical operation and obtaining a certain result.
Rule of thumb, Heuristic, a rule that doesn't always apply, but that shows a tendency or probability.
Game mechanic, a rule to help govern a game.
Military rule
Ruler, a straight edge used for measurement.

Rule may also be:

To control a country, for example through a Dictatorship or Monarchy
In the field of Artificial intelligence, a database of rules can be used to govern the behavior of a system
A computer project with the goal of compiling/adapting programs in order to make them use less resource (under linux) in order to get old computers(5 yesrs old or more) usable with up to date software (usefull for scool, or where there is a big number of computer required(computers aren't cheap))