A more thorough explanation:

Definition: A federal crime is a criminal offense that is defined by a federal statute. These crimes are typically listed in Title 18 of the U.S. Code.

Examples:

• Bank robbery
• Drug trafficking across state lines
• Mail fraud

Bank robbery is a federal crime because it involves stealing from a federally insured bank. Drug trafficking across state lines is also a federal crime because it involves crossing state borders, which falls under federal jurisdiction. Mail fraud is a federal crime because it involves using the U.S. Postal Service to commit fraud.

These examples illustrate how federal crimes can involve a variety of criminal activities that cross state lines or involve federal agencies or institutions.