"Congress divides its legislative, oversight, and internal administrative tasks among more than 200 committees and subcommittees. Within assigned areas, these functional subunits gather information; compare and evaluate legislative alternatives; identify policy problems and propose solutions; select, determine, and report measures for full chamber consideration; monitor executive branch performance (oversight); and investigate allegations of wrongdoing. […] There are three main types of committees: standing, select or special, and joint. (Party committees, task forces, and congressional Member organizations--informal groups--are not addressed here.) […] Most committees form subcommittees to share specific tasks within the jurisdiction of the full committee. Subcommittees are responsible to, and work within the guidelines established by, their parent committees. In particular, standing committees usually create subcommittees with legislative jurisdiction to consider and report bills. They may assign their subcommittees such specific tasks as the initial consideration of measures and oversight of laws and programs in the subcommittees' areas."
CRS Report for Congress, 98-241