Coronaviruses are a family of viruses that can cause serious diseases like SARS and MERS. They were first identified in the 1960s. The novel coronavirus, which causes COVID-19, is the seventh type known to infect humans. There are four types of coronaviruses, with the first two infecting mammals like bats, pigs, cats, and humans. The viruses in this family have very similar genomes, with only slight differences. Some coronaviruses are responsible for about 30% of upper respiratory tract diseases in humans. Overall, coronaviruses can cause infections in the respiratory and gastrointestinal tracts.