Sometimes businesses can be unfair to their employees. It is easy for a large company to begin to develop policies that are not beneficial for those people at the bottom. A laborers union is a system which is meant to help keep company policies in check. A union is formed when the working class of a company, or in many cases a whole industry band together to make things fair for the people whose shoulders the business rests on. Alone, each individual is just a worker but when banded together a union becomes an entity that can not be ignored.
The most powerful weapon that the laborers union has against a corrupt system is the strike. A strike is when the union decides that rather than attend work, the members are going to actively protest whatever injustice it is that they disagree with so much that they were driven to that point. When a worker signs up for a union they are agreeing to automatically act with the decisions of the union. If the union votes to strike, all members are required to participate, regardless of which way that they voted. With a large portion of the workers unionized, the company is forced to make negotiations when there is a strike, otherwise they lose money from lack of work.
Te concept of a laborers union exists so that the average working man gets what he deserves. The operation and fate of a company lies within the hands of the workers. They are the ones who actually get things done, therefore they are the source of a businesses income. Unions serve to demonstrate that point. If workers are not offered fair wages and good working conditions, the work may simply just stop in mass. This keeps company executives and policies in check.