National Hairball Awareness Day is observed worldwide every last Friday of April. It was created by the National Museum of Health and Medicine in Silver Spring, Maryland, to educate the public about trichobezoars, which are masses of hair trapped in the gastrointestinal system. The day primarily targets cat owners, emphasizing the importance of understanding hairballs and their potential dangers, particularly for pets like cats, rabbits, and cud-chewing animals. Typical customs include grooming pets regularly, ensuring a fiber-rich diet, and consulting veterinarians if pets show signs of distress related to hairballs. Since its inception, various veterinary organizations and clinics have supported this awareness day, which has evolved from a focus on medical curiosities to practical education for pet owners.