preempting

Preempting refers to taking action to prevent or forestall a perceived threat, opportunity, or competition by acting before it can materialize or be exploited. The term originates from Latin praeemere, "to take beforehand," and entered English via Old French. In common usage it connotes urgency and decisiveness, often implying a strategic or anticipatory motive.

In law, preemption is a doctrine by which higher authority displaces or overrides lower-level rules. In the United States, federal preemption arises from the Supremacy Clause, and can be categorized as field preemption (where federal law occupies a regulatory field) or conflict preemption (where compliance with both is impossible or would cause harm).

In computing, preemption refers to preemptive multitasking, where an operating system can interrupt a running process to schedule another, typically higher-priority, task. This allows responsive systems and real-time behavior but requires careful synchronization to avoid data races and priority inversion. Non-preemptive systems rely on a process to yield voluntarily.

In military and geopolitical contexts, a preemptive strike seeks to neutralize an imminent threat by acting before it fully develops. It is distinct from preventive war, which aims to prevent a future threat even if no immediate danger exists.

In corporate finance, preemptive rights give existing shareholders the option to buy new shares to maintain their proportional ownership when a company issues additional equity, protecting against dilution.

See also: preemption, preventive war.