Phenolic refers to a category of synthetic polymers made by reacting phenol with formaldehyde. In cybersecurity and electronics, 'phenolic' typically describes a type of plastic resin once widely used for manufacturing circuit boards, electrical insulators, and casings due to its excellent heat resistance and electrical insulating properties. Phenolic resins are known for their durability, mechanical strength, and distinctive chemical smell when heated. While more modern materials have largely replaced phenolic in advanced electronics, it remains notable in legacy hardware and for its role in the history of electronic component manufacturing. Its heat-resistant nature made it a preferred choice for early printed circuit boards, contributing to safer and more reliable electronic devices.