This chapter examines the complex experience of pain, focusing on how aberrations in this crucial protective system lead to maladaptive states. It begins by defining nociception, detailing the peripheral mechanisms of pain transmission involving nociceptors and primary afferent fibers, and by exploring the central mechanisms of pain processing within the spinal cord and the brain. This chapter then addresses various methods for managing both acute and chronic pain. Building on these fundamentals, this chapter investigates conditions where pain perception is disturbed, including neuropathic syndromes like phantom limb pain and fibromyalgia. Finally, this chapter discusses congenital insensitivity to pain (CIP), a rare condition, to highlight the essential role that pain perception plays in ensuring our survival.