Trade unions negotiate with employers on behalf of union members to agree wages, work rules, complaint procedures, rules governing hiring, firing and promotion of workers, benefits, workplace safety and other policies.
Members benefit from the strength and security that comes from people working together to tackle problems.
Union members agree a common aim of what they want to achieve. This might be about pay or bullying at work or challenging unfairness for eg. Representatives from the union gather evidence about the issue and present it to their employer. They discuss the matter with the employer to reach an agreement.
If the employer refuses to reach an agreement, union members can broaden their campaign to win wider support in the workplace. This may be with the public or at a national level with MPs and in government.
Trade unions also provide legal representation for works, for e.g. to win compensation in the event of an accident or injury at work. May trade unions also provide other benefits and discounts on services for their members. You can think of Trade unions as your insurance policy.