Envelope stress response is a conserved biological mechanism in bacteria that detects and responds to damage or perturbations affecting the cell envelope, including the membrane, peptidoglycan, and outer membrane. It represents a research field investigating the intricate signal transduction pathways, protein systems (e.g., PSP, Rcs, sigma factors), and regulatory networks employed by bacteria to maintain envelope integrity, adapt to environmental challenges, and contribute to processes such as virulence and antimicrobial resistance.