Congress lacks the necessary time and expertise to produce legislation for every area of conduct in society. This is especially true for highly-specialized and complex industries. It is for this reason that Congress, or occasionally the Executive Branch, delegates regulating powers to existing governmental agencies. At times they also create new commissions or agencies to cope with emerging trends.
For example, after the September 11, 2001, terrorist attacks, the 9-11 Commission (also known as the National Commission on Terrorist Attacks Upon the United States) was created in a joint effort of the executive and legislative branches. The Commissions purpose was to provide a comprehensive account of the terrorist attacks as well as recommendations to guard against future attacks. It developed a set of 41 recommendations for improvement of homeland security, ranging from emergency preparedness and response to reforming government institutions to changing foreign policy.
In the case of the 9-11 Commission, its report was a direct response to its purpose in accounting for terrorist attacks. As a legal researcher, it is important to understand the role of different administrative agencies because it will inform your understanding of the documents that each agency or commission produces.