A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaeaSince Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants, and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898,more than 6,000 virus species have been described in detail, of the millions of types of viruses in the environmentViruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity.The study of viruses is known as virology, a subspeciality of microbiology.And also included corona viruses information in deatils and other viruses information written by mr vivek kumar pandey shambhunath