A trade union is an organisation formed at the request and on the initiative of workers to improve working and living conditions and to defend workers' rights and interests, by workers acting collectively and in cooperation with the employer. Trade unions are independent of employers, public authorities and other organisations.

The benefits of trade union membership are particularly clear in situations where the employer wants to change the terms of the employment contract, for example by reducing pay. In such cases, trade union members can appoint a trustee, who has received special training, to negotiate on their behalf with the employer and who can be assisted by a trade union lawyer if necessary.