At the end of 2019, there was a sudden outbreak of pneumonia in China, which was reported to be caused by the new type of coronavirus, called SARS-CoV-2. This rapidly spreading virus has caused a public health crisis, and turned into a pandemic in a short time through the infected people traveling outside of China. It is believed that bats, which are the reservoir of the new coronavirus and provides a gene pool for betacoronaviruses, transmitted the SARS-CoV-2 to an intermediate host called pangolin, which in turn transmitted it to humans. Although not fully clarified yet, it is currently the most valid hypothesis that pangolin provided a partial S gene mutation to new coronavirus which is transformed into the final SARS-CoV-2 form that can infect humans. The epitope-paratope interaction is achieved through the binding of S glycoprotein of SARS-CoV-2 to the ACE2 receptors in the epithelial tissues of the human respiratory system. Following its entry into cells, SARS-CoV-2 completes its life cycle consisting of transcription, translation and replication stages, and transfers the next generation of infective virions out of the cell to infect other susceptible cells. The viral proteins, which play an important role in the life cycle of SARS-CoV-2, manage the activities of receptor binding specificity, proteolytic activation, endocytosis activity and inhibition of the host's natural immune response, and shape the pathogenesis of the disease in this way. The most important factor that distinguishes COVID-19 infection caused by SARSCoV- 2 from other coronavirus infections is believed to be due to the structural and non-structural protein activities of SARS-CoV-2. As a result, the zoonotic coronavirus species, such as SARS-CoV, MERSCoV, and SARS-CoV-2 that have emerged in recent years have caused a significant public health problem. Depending on the mutations in coronaviruses, new species are likely to emerge over time. Therefore, detailed and ongoing studies on the biology, pathogenesis and epidemiology of coronaviruses are needed.