Congressional oversight is oversight by the United States Congress over the Executive Branch, including the numerous U.S. federal agencies. Congressional oversight includes the review, monitoring, and supervision of federal agencies, programs, activities, and policy implementation. Congress exercises this power largely through its congressional committee system. Oversight also occurs in a wide variety of congressional activities and contexts. These include authorization, appropriations, investigative, and legislative hearings by standing committees; specialized investigations by select committees; and reviews and studies by congressional support agencies and staff.
More info on Wiki
hope this helps:)