A policy is a plan of action for tackling political issues. It is often initated by a political party in government, which undergoes reforms and changes by interested actors (for example, opposition parties and lobby groups).

In AI planning and reinforcement learning, a policy prescribes a non-empty deliberation (sequence of actions) given a non-empty sequence of states.

Types of policy include:

• stationary (resp. non-stationary)
• deterministic (resp. stochastic, randomized and sometimes non-deterministic)
• memoryless (e.g. non-stationary)
• causal (resp. non-causal)
• index
• opportunistic (resp. non-opportunistic)

These qualifiers can be combined, so for example you could have a stationary-memoryless-index policy.

In enterprise architecture for systems design, policy appliances are technical control and logging mechanisms to enforce or reconcile policy (systems use) rules and to ensure accountability in information systems.