Before the beginning of 2020, many people had never heard the word "coronavirus." But coronaviruses are not new. Researchers have been studying coronaviruses for decades. As COVID-19 appeared in 2019, lives changed forever. However, long before the World Health Organization announced the COVID-19 pandemic, coronaviruses had been making people sick in familiar ways, such as with the common cold. This episode discusses COVID-19, as well as all coronaviruses.