Congress creates committees to streamline and maintain organization in the process of making bills. Committees also provide a natural filter by assigning a small group of people to focus intensely on one area.
More than 8,000 bills are introduced into Congress each year. If all of the members of Congress were forced to closely examine each bill, the process would be very slow, and some bills would virtually go un-reviewed. By having committees, Congress can give new bills to committees with special interests or expertise in the area of the bill, who can then do the necessary research and scrutinize it to see if would be in the best interest of the people for Congress to vote on passing the bill into law.
There are several types of committees in Congress. Standing committees are committees that are somewhat permanent and continue from session to session. Select committees are temporary committees formed for a special purpose. Conference and joint committees are committees comprised of both houses. The primary difference between the two is that a conference committee is formed for the two houses to resolve disputes about various versions of the same law. Joint committees are formed when the two houses have business to conduct with one another.