Allergens are substances that trigger an allergic reaction in the immune system of certain individuals. Common allergens include pollen, dust mites, pet dander, food proteins, and insect venom. When a person with allergies comes into contact with an allergen, their immune system overreacts and produces antibodies to fight off the perceived threat, leading to symptoms such as sneezing, itching, hives, and in severe cases, anaphylaxis. Allergen research aims to identify and understand the mechanisms by which allergens trigger immune reactions, develop diagnostic tests to identify specific allergens, and discover new treatments to manage and prevent allergic reactions.