Picornaviruses are a family of small, single-stranded RNA viruses that can cause various diseases in humans and animals. They are known for their resilience and can survive in harsh environments. Common examples of diseases caused by picornaviruses include polio, hand, foot, and mouth disease, and common cold. These viruses are typically transmitted through the fecal-oral route or respiratory droplets. Once inside the host, they can replicate quickly, leading to symptoms that range from mild to severe. Due to their ability to mutate, picornaviruses pose challenges for vaccine development and disease control.