Insect repellents are substances applied to skin, clothing, or other surfaces to deter insects from biting or landing on these surfaces. They work by either masking the scent of the host, making it difficult for insects to find and bite, or by physically repelling insects through the release of volatile compounds that interfere with the insect's sense of smell or taste. Insect repellents are commonly used to protect against mosquito-borne diseases such as malaria, dengue fever, and Zika virus, as well as to prevent discomfort and allergic reactions caused by insect bites. The effectiveness and safety of insect repellents are important considerations in their development and use.