The N-end rule is a biological theory that outlines the degradation of proteins within a living organism based on the amino acid that constitutes the N-terminus. This concept is now known as the "N-end degradation pathway" to avoid confusion with the N-end rule. Other synonyms for this theory include the "N-terminal rule," "N-end pathway," and "N-degron pathway." The N-end degradation pathway plays a crucial role in maintaining cellular homeostasis by degrading damaged proteins, regulating gene expression, and responding to cellular stressors. Understanding this pathway and its associated synonyms is essential for the development of therapies and drugs that target protein degradation for various diseases and conditions.