Trade unions originally formed to protect workers from unfair treatment by employers. Over time, unions fought for better wages and working conditions through collective bargaining. Unions serve two main functions - redistributing wealth through higher pay and ensuring job security. They are permanent associations that work to improve economic benefits and living standards for members. Unions have taken on additional roles like raising social status, contributing to development. Different types of unions include craft, industrial, general and staff unions organized based on skills, industries or common status.