virus

A virus is an infectious agent that is submicroscopic in size and can only replicate within the living cells of a host organism. These entities have the capability to infect a wide range of life forms, including animals, plants, and microorganisms such as bacteria and archaea. Viruses are ubiquitous, present in nearly every ecosystem on the planet, and represent the most abundant category of biological entities. Since the publication of Dmitri Ivanovsky's 1892 article, which detailed a non-bacterial pathogen affecting tobacco plants, and the subsequent identification of the tobacco mosaic virus by Martinus Beijerinck in 1898, over 11,000 distinct virus species have been thoroughly documented. The scientific discipline dedicated to the study of viruses is referred to as virology, which is a specialized branch of microbiology.