Viruses are parasitic biological entities that rely on host cells to reproduce. Upon entering a cell, the virus utilizes the cellular machinery to replicate its genetic material and generate new viral particles.
This often results in cellular damage and can trigger diseases in hosts, including humans, animals, or plants.
The ability of viruses to transfer genetic material between cells can have evolutionary implications, and some viruses are used in genetic research. However, many viruses are pathogens that can cause severe illnesses in infected organisms.