Why do viruses evolve quickly?

Evolution of viruses:

1. Viruses are microscopic infectious microbes that infect all living cells.
2. Viral genomes are made up of either DNA or RNA molecules.
3. Viruses evolve quickly as they mutate rapidly compared to other organisms.
4. Viral cells lack proofreading mechanisms that aid in repairing sequence errors.
5. As viruses multiply rapidly, the scope for mutations is high and thus they evolve at a faster rate.