The life cycle of a virus is the same as other pathogens. They can often survive outside a host for long periods of time. When they do infect a suitable host cell or cells, they replicate themselves within the cell thousands of times. They do not divide and reproduce like cells, but complete the lytic pathway.
Other types of virus called phages either join their DNA to that of their host or leave small circles of their DNA in the cytoplasm of their host cell or cells. This is called the lysogenic pathway. When these cells divide the DNA is copied. Later in the life cycle the viral DNA is copied and the lytic cycle detailed above begins.