Muckrakers were journalists and other writers that wrote during the Progressive Era, or during the pre-World War I era. They based their writing on exposing the corruption in businesses and governments, providing detailed and accurate accounts of what was going on.
Many Muckrakers would expose big businesses to treating their workers unfairly or even child labor. Since Muckrakers would expose businessmen and politicians, many strived to be better in fear of being exposed and having their businesses and schemes become no longer.
Some politicians even ended up advocating for some of the people being used, like the workers and the children. With this, along with the public outcry of people, the legislation would end up passing laws that protected workers.