Legislative History is made up of documents preceding and surrounding enactment of a law. These documents generally include bills, public laws, floor debates, committee hearings and reports, and are used to determine the legislative intent of a statute.
Legislative Process Overview page by Congress.gov includes a diagram and a 5-minute video (with transcript) of the legislative process, as well as links to short videos on topics such as Committee Consideration and Resolving Differences, and to many resources including a Glossary and additional House and Senate Resources.
Compiling a Federal Legislative History: A Beginner's Guide is a Research Guide created by the Library of Congress, focused on relevant documents and sources of federal legislative histories.
How Our Laws Are Made was prepared by the Office of the Parliamentarian of the U.S. House of Representatives in consultation with the Office of the Parliamentarian of the U.S. Senate. This provides an outline of the numerous steps involved in the federal lawmaking process from an idea for a legislative proposal through its publication as a statute.
Federal Legislative History Research: A Practitioner's Guide to Compiling the Documents and Sifting for Legislative Intent by the Law Librarians' Society of Washington, D.C.
Congressional Glossary includes definitions of terms used in the legislative process.