When someone does something really bad, like stealing or hurting someone, they might have broken a law. Laws are rules that tell us how to behave in our society, and they are created by the government.
There are different levels of laws. Some laws apply only to a certain city or state, while others apply to the whole country. When someone breaks a law that applies to the whole country, we call it a federal crime.
So, federal crimes are the most serious type of lawbreaking, and they are dealt with by the federal government. This means that instead of local police or courts handling the situation, special government agents (such as the FBI) will investigate and prosecute the crime.
Examples of federal crimes include things like terrorism, drug trafficking, and bank robbery. It's important to remember that most people will never commit a federal crime, and the vast majority of us will never interact with the federal criminal justice system.