A hornet sting is a painful injury caused by the venom injected from the stinger of a hornet, which is a type of wasp. Hornets are larger than typical wasps and can be aggressive when defending their nests. The sting can cause immediate pain, swelling, and redness at the site, and in some cases, it may lead to allergic reactions. The venom contains proteins that affect skin cells and the immune system, leading to inflammation. Most people experience mild symptoms, but those allergic to bee stings may face severe reactions, requiring medical attention. It's important to treat stings promptly to reduce discomfort.