Hearings are meetings or sessions of a committee of Congress and are usually open to the public. There are four reasons for conducting hearings:
Consider new legislation - "Legislative" hearings consider measures or policy issues that may become public law.
Review current laws - "Oversight" hearings" review or study a law, issue, or an activity, often focusing on the quality of federal programs and the performance of government officials.
Examine event/situation -- "Investigative" hearings are conducted when there is a suspicion of wrongdoing on the part of public officials acting in their official capacity, or private citizens whose activities suggest the need for a legislative remedy and often result in legislation which addresses the problems uncovered.
Confirm nominations -- "Confirmation" hearings are held to advise on nominations to executive and judicial positions.
When bills are proposed the bill can be referred to a specific committee for study. The committee in turn may decide to hold hearings.
Slip Laws (AE 2.110) - the first publication of an approved bill enacted by Congress, signed by the President, and given a public-law number.
Statutes at Large (AE 2.111) - Slip laws are compiled annually and published in final form in the Statutes at Large, a chronological compilation of all the laws of one session of Congress.
United States Code (Y 1.1/5) - Finally, the law is codified in the United States Code (the original law and all subsequent amendments). The Code is arranged by subject into 50 titles and is fully revised every six years. It has a general index that provides subject access and popular names of acts.