Strike action, also called labor strike, labour strike, or simply strike, is a work stoppage caused by the mass refusal of employees to work. A strike usually takes place in response to employee grievances. Strikes became common during the Industrial Revolution, when mass labor became important in factories and mines. As striking became a more common practice, governments were often pushed to act (either by private business or by union workers). When government intervention occurred, it was rarely neutral or amicable. Early strikes were often deemed unlawful conspiracies or anti-competitive cartel action and many were subject to massive legal repression by state police, federal military power, and federal courts. Many Western nations legalized striking under certain conditions in the late 19th and early 20th centuries.

Strikes are sometimes used to pressure governments to change policies. Occasionally, strikes destabilize the rule of a particular political party or ruler; in such cases, strikes are often part of a broader social movement taking the form of a campaign of civil resistance. Notable examples are the 1980 Gdańsk Shipyard and the 1981 Warning Strike led by Lech Wałęsa. These strikes were significant in the long campaign of civil resistance for political change in Poland, and were an important mobilizing effort that contributed to the fall of the Iron Curtain and the end of communist party rule in eastern Europe.