Cowpox is a viral infection caused by the cowpox virus, which primarily affects cows but can also infect humans. The disease is characterized by the appearance of pustules on the skin, similar to those seen in smallpox. Cowpox is generally mild and can be transmitted through direct contact with infected animals or contaminated materials. Historically, cowpox played a significant role in the development of the smallpox vaccine. In the late 18th century, Edward Jenner discovered that exposure to cowpox could provide immunity against smallpox, leading to the practice of vaccination. This breakthrough significantly reduced smallpox cases and ultimately contributed to its eradication.