Viruses are considered to be a transitional group between living and non-living. They exhibit characteristics of life, such as replication and evolution, only when they infect a host cell. Outside of a host, they exist as inert particles consisting of genetic material (DNA or RNA) enclosed in a protein coat. They cannot carry out metabolic processes on their own and do not have cellular structures. When a virus infects a host cell, it takes over the cell’s machinery to replicate itself, which is a key aspect of living organisms. However, outside of a host, they do not show any of these properties and remain dormant. This dual nature places them in a unique position on the boundary between living and non-living matter.