An RNA virus is a type of virus that uses ribonucleic acid (RNA) as its genetic material. Unlike DNA viruses, which have deoxyribonucleic acid (DNA), RNA viruses can replicate quickly and often mutate, making them adaptable to changing environments. They can infect a wide range of hosts, including animals, plants, and humans. Examples of RNA viruses include the influenza virus, which causes the flu, and the coronavirus, responsible for COVID-19. These viruses can lead to various diseases and are often transmitted through respiratory droplets, contaminated surfaces, or direct contact with infected individuals.