This document provides an overview of plant and animal viruses. It discusses the morphology, structure and life cycles of tobacco mosaic virus (TMV) and rhabdovirus as examples. TMV is a helical plant virus that infects tobacco plants and causes mosaic symptoms on leaves. It has a rod-shaped structure with RNA inside a protein coat. Rhabdovirus is an animal virus with a bullet-shaped structure and negative-sense RNA genome. It discusses how viruses replicate using the host cell's machinery and cause disease in plants and animals. In conclusion, viruses are non-living particles that can infect all types of life and replicate using host cells.