Also worth noting that, depending on the virus, particles outside a host can often survive for hours or sometimes days. To get infected by direct inhalation you’d need to be fairly close to a sick person when they were shedding virus into the air – i.e. to be very close to them in both space and time. To get infected through surface contamination the time requirement is much less stringent: you only need to be where an infected person was fairly recently. If you don’t have good hand/face/mouth hygiene, they can infect you without your ever seeing them or knowing they were there.
Also worth noting that, depending on the virus, particles outside a host can often survive for hours or sometimes days. To get infected by direct inhalation you’d need to be fairly close to a sick person when they were shedding virus into the air – i.e. to be very close to them in both space and time. To get infected through surface contamination the time requirement is much less stringent: you only need to be where an infected person was fairly recently. If you don’t have good hand/face/mouth hygiene, they can infect you without your ever seeing them or knowing they were there.