House and Senate subcommittees hear testimony on proposed legislation in order to determine the need for new legislation in a particular area and to hear the views of various persons or organizations interested in the legislation.
Hearings can provide a wealth of information for background research into the issue Congress is addressing.
Hearings are held for almost all substantive legislation and transcripts of most hearings (including exhibits provided by those testifying) are published. For interpreting enacted legislation, hearings are less useful than other legislative documents because they focus on the views of the parties testifying rather than the views of the committee or Congress.
~Source: UCONN Meskill Law Library
The proceedings of congressional committee hearings are published. The best source for published hearings is ProQuest Congressional. Not all committee activity is officially published and/or published hearings might not be available right away, so there are a number of other sources for finding transcripts or watching congressional hearings.