Three coronaviruses, originating in animals, have crossed the species barrier to cause deadly pneumonia in humans within the last two decades; SARS (Severe Acute Respiratory Syndrom), MERS (Middle East Respiratory Syndrome) and now the current pandemic of COVID-19 / nCov-2019 / SARS-CoV-2.
But exactly how does the nCov-2019 infect us? The spikes (that can be seen on all the current illustrations of coronavirus) on its surface act as keys in locks by binding to specific receptors (ACE2) on the surface of our epithelial cells. Watch this animation and learn more. It is based on the recent, scientific literature within the field, but as it is my interpretation and some details have been simplified, it might not reflect the truth 100 %.