Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a lineage B betacoronavirus responsible for the coronavirus disease 2019 (COVID-19) pandemic that began in 2020. The earliest known cases occurred in Wuhan, China, in late 2019. Infections had spread to every continent except Antarctica by March 2020. In the first 2 years of the pandemic, the World Health Organization received reports of more than five million deaths. The virus is closely related to bat and pangolin coronaviruses and shares 79% genome similarity to SARS-CoV-1. Since its emergence, it has evolved into distinct lineages that continue to circulate globally. Three distinct features of SARS-CoV-2 hampered control efforts, in contrast to other zoonotic coronavirus outbreaks. First, SARS-CoV-2 has high transmissibility with an initial basic reproductive number in the range 2.0–2.2 that is higher than seasonal and pandemic influenza. Second, SARS-CoV-2 produced relatively mild or asymptomatic infection, resulting in occult community spread. Third, transmission occurred early in the course of infection and disease, sometimes before symptoms appeared, leading to rapid epidemic spread. A fourth ominous feature unique to this virus is the occurrence of an unexplained, often months-long postinfectious syndrome characterized by multiple neuropsychological, cardiopulmonary, and other symptoms. Unprecedented use of stringent public health and social measures in 2020 was able to suppress transmission and bought time for vaccine development. Billions of vaccine doses were administered through 2021, saving millions of lives. Circulating strains of SARS-CoV-2 evolved into a series of variants with increased transmissibility and the ability to evade population immunity resulting from vaccinations and epidemics of previous variants. Disease burden has declined in the postpandemic era. Although the incidence of serious illness remains substantial, it can be reduced by booster vaccinations.