A labor union or trade union is an organization formed for the purpose of collectively representing the interests of a group of workers. In particular this can include collectively bargaining with employers in order to agree rates of pay and other conditions of employment. Conservatives tolerate the right of workers to form unions but recoil when they become too liberal, too corrupt, or too authoritarian over their members. Liberals, Democrats, and some Republicans support them, and use their influence to encourage union members to support liberal causes and candidates financially.
There are generally two types of unions, private sector unions and public sector unions; some unions have members in both the private and public sectors.