An organized association of workers in a particular trade or profession. Unions represent employees in negotiations with employers. In the USA they are referred to as labor unions. In Britain in the late 18th century groups and clubs of working‐men in skilled trades developed, to regulate admission of apprentices and sometimes to bargain for better working conditions. During the wars with France (1793–1815) Combination Acts suppressed any such activity, but on their repeal in 1824 limited trade union activity became possible in certain crafts. By 1861 a number of trade unions of skilled workers existed in Britain, forming the Trades Union Congress (TUC) in 1868, gaining some legal status in 1871, and the right to picket peacefully in 1875. With the development of mass‐production methods in the industrialized countries large numbers of semi‐skilled and unskilled workers were recruited, and from the 1880s attempts were made to organize these into unions. These attempts were more successful in Britain and in Europe than in the USA, where cheap immigrant labour was for long available. Unions emerged in Australia and New Zealand and in other British dominions in the 19th century. As industrialization proceeded in other countries so trade unions developed, although in South Africa trade union activity among Black workers was illegal until 1980. In the former Soviet Union and communist Eastern Europe 90% of industrial workers belonged to government‐controlled unions. Elsewhere, union membership fluctuates with political and economic vicissitudes, especially in developing countries.

Trade unions are funded by membership subscriptions and are usually run by an elected executive and full‐time officials, and elected workplace representatives (shop stewards in Britain). Their main economic objectives are to attain good wages, good working conditions, and secure employment for their members. Trade unions aim to achieve their workplace industrial relations objectives through collective bargaining, supported when necessary by industrial action. A significant development since World War II was the increasing participation of trade unions in government and tripartite bodies at national or industry level. However, in such nations as the USA and UK union membership and influence declined in the late 20th century, especially in the private sector.