What makes a professional journalist? Ethics

With all types of people publishing news and information on the web, how do you distinguish who is a professional journalist?

After all, bloggers have broken some big stories before mainstream news organizations, for example. Many of them bring value to their work. In other words, how do journalists justify calling themselves professionals, and how do they differentiate themselves from amateurs and drivelers?

One important way is by their adherence to ethical standards of the profession. Another is by knowledge of how to investigate and verify information. Professionals with the highest standards should be dedicated to more than being first and generating page views.