Rule

A rule is:

* Rewrite rule, in generative grammar and computer science
* Standardization, a formal and widely-accepted statement, fact, definition, or qualification
* Operation, a determinate rule ("method") for performing a mathematical operation and obtaining a certain result (Mathematics, Logic)
**Unary operation
**Binary operation
* Rule of inference, a function from sets of formulae to formulae (Mathematics, Logic)
* Rule of thumb, principle with broad application that is not intended to be strictly accurate or reliable for every situation. Also often simply referred to as a "rule"
* Moral, an atomic element of a moral code for guiding choices in human behavior
* Heuristic, a quantized "rule" which shows a tendency or probability for successful function
* A regulation, as in sports
* Procedural law, a ruleset governing the application of laws to cases
** A law, which may informally be called a "rule"
** A court ruling, a decision by a court
* In the U.S. Government, a regulation mandated by Congress, but written or expanded upon by the Executive Branch.
* Norm (sociology), an informal but widely accepted rule, concept, truth, definition, or qualification ("social norms, legal norms, coding norms")
* Norm (philosophy), a kind of sentence or a reason to act, feel or believe
* "Rulership" is the concept of governance by a government:
** Military rule, governance by a military body
** Monastic rule, a collection of precepts that guides the life of monks or nuns in a religious order where the superior holds the place of Christ

Other uses

* Rule (song), a song by rapper Nas
* Ruler, an instrument for measuring lengths
* Rule, a component of an astrolabe, circumferator or similar instrument
* Rule of thumb, Acquisition, a set of guidelines intended to ensure the profitability of businesses owned by the ultra-capitalist Ferengi in the fictional Star Trek universe
* "The Rules", a bestselling self-help book
* RULE Project (Run Up-to-date Linux Everywhere) is a project that aims to use up-to-date Linux software on old PCs
* Rule engine, a software system that helps managing business rules
* Ja Rule, a hip hop artist
** "R.U.L.E.", a 2005 greatest hits album by rapper Ja Rule