Agencies are often described as the fourth branch of government. This is the work of agencies is the work of the federal government that most closely affects our lives.
Most agencies are administered through the executive branch, which executes the laws, and the work of agencies allows for this to happen. Agencies provide rules and regulations and decisions that help with this. Some definitions from Merriam Webster:
Regulation: an authoritative rule dealing with details or procedure
Rule: A prescribed guide for conduct
Unified Agenda: Semi-annual compilation about regulations under development by agencies
The Executive Office of the President was established by President Franklin D. Roosevelt in 1939. The EOP now consists of such entities as the Council of Economic Advisers, the Office of National Drug Control Policy, the Office of Science and Technology Policy, and the Office of Management and Budget.
The document below has greater detail on how to search these effectively.
The Unified Agenda of Regulatory and Deregulatory Actions is published every spring and fall and announces federal agencies' regulatory plans. Beginning in 2007, the Unified Agenda only includes rulemaking actions with significant economic impact.
There are quite a few ways to track federal regulations. Some of the resources listed below are official government sites, while others are tools that aggregate information from many sources (including government documents) to allow users to monitor regulatory activities.