Coronaviruses are pathogens of humans, most domestic and wild animals. Bat coronaviruses came into spotlight during SARS pandemic as bats proved to be the source and reservoir of numerous coronaviruses with zoonotic potential. Taxonomy classifies coronaviruses in four genera; Alphacoronavirus and Betacoronavirus are pathogens of humans, bats and other mammals, while genera Gammacoronavirus and Deltacoronavirus predominantly infect birds. Bats are unique hosts of coronaviruses because they have a specific immune system and live in diverse and dense colonies. Southeast Asia is characterized by biodiversity of bats and consequently their coronaviruses; three of four recent outbreaks caused by emergent coronaviruses of humans and livestock originated in China. Mutation, recombination and natural selection are mechanisms of molecular evolution of coronaviruses. Livestock and pet coronaviruses cause respiratory and enteric diseases and are prone to emergence of new strains, resulting in high mortality rates and low effectivness of prophylaxis. As such they are compelling model for a better, holistic understanding of coronaviruses and future prevention of new strains with epidemic potential.