Which is a difference between bacteria and viruses that show that bacteria are living organisims and viruses are not?

One key difference between bacteria and viruses is that bacteria are single-celled organisms that can reproduce on their own through cell division, which is a hallmark of living organisms. In contrast, viruses lack cellular structures and cannot reproduce independently; they require a host cell to replicate. Additionally, bacteria can carry out metabolic processes, while viruses do not possess any metabolic machinery and are inactive outside of a host. These characteristics underscore that bacteria are considered living organisms, whereas viruses are classified as non-living entities.