A more thorough explanation:

The affects doctrine is a principle in constitutional law that allows Congress to regulate activities within a state that have a significant impact on interstate commerce. This principle is based on the idea that even intrastate activities can affect the economy of the entire country.

For example, if a company in one state is producing a product that is sold in many other states, Congress can regulate that company's activities to ensure that the product is safe and meets certain standards. Similarly, if a state is allowing pollution that affects the air or water quality in neighboring states, Congress can regulate that state's activities to protect the health and well-being of people in other states.

The affects doctrine is important because it allows Congress to address issues that affect the entire country, even if those issues originate in a single state. By regulating activities that have a significant impact on interstate commerce, Congress can ensure that the economy and the environment are protected for everyone.