A trade union, also known as a labor union or a workers' union, is an organization that represents and protects the rights and interests of employees in their workplace. Some other synonyms for trade union include guild, association, brotherhood, and professional organization. Guilds traditionally referred to groups of skilled workers in closely related industries such as carpenters, blacksmiths, and musicians. Brotherhood can also imply a sense of solidarity and camaraderie among members. Association and professional organization tend to have a more formal and business-like connotation, although all of these terms convey the idea of collective action and shared advocacy.