DEET is a chemical compound commonly used in insect repellents to protect against bites from mosquitoes, ticks, and other pests. It was developed by the U.S. Army in the 1940s and has since become one of the most effective and widely used insect repellents worldwide. DEET works by interfering with the insects' ability to detect humans, making it less likely for them to land on treated skin. When using DEET, it is important to follow the instructions on the product label for safe application. It is available in various concentrations, with higher percentages providing longer-lasting protection. While generally considered safe for adults and children, some may experience skin irritation or allergic reactions, so testing a small area first is advisable.