What is meant by yellow journalism and what was its purpose?

What is meant by yellow journalism and what was its purpose?
Yellow journalism or the yellow press is a type of journalism that presents little or no legitimate well-researched news and instead uses eye-catching headlines to sell more newspapers. Techniques may include exaggerations of news events, scandal-mongering, or sensationalism. By extension "Yellow Journalism" is used today as a pejorative to decry any journalism that treats news in an unprofessional or unethical fashion.