Rule

Rule and ruling usually refers to standards for activities, such as policies and guidelines. They may refer to:

Human activity

Business rule, a rule pertaining to the structure or behavior internal to a business
School rule, a rule that is part of school discipline
Sport rule, a rule that defines how a sport is played
Game rule, a rule that defines how a game is played
Moral, a rule or element of a moral code for guiding choices in human behavior
Norm (philosophy), a kind of sentence or a reason to act, feel or believe
Rule of thumb, a principle with broad application that is not intended to be strictly accurate or reliable for every situation
Unspoken rule, an assumed rule of human behavior that is not voiced or written down

Rule of inference or transformation rule, a term in logic for a function which takes premises and returns a conclusion
Phrase structure rule or rewrite rule, used in some theories of linguistics
"Rule X" elementary cellular automaton, where X is a number between 0-255 characterizing a specific model (e.g. Rule 110)
Ruler, or "rule"; a distance measuring device
Phonological rule
Social norm, explicit or implicit rules used within society or by a group

Advance tax ruling, a tool for conforming taxation arrangements
Court order, a decision by a court
Government
In rulemaking by the federal government of the United States, a regulation mandated by Congress, but written or expanded upon by the executive branch
Law, which may informally be called a "rule"
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
Procedural law, a ruleset governing the application of laws to cases
Rule of law, government based not on arbitrary decisions of officials but on laws