Viruses can be classified in several ways. The most useful is probably by the type of nucleic acid the virus contains, but they can also be classified:
by their geometry
by whether they have envelopes
by the identity of the host organism they can infect
by mode of transmission
by the type of disease they cause
Classification by type of constituent nucleic acid (i.e. by genome type), with examples:
... over, there are 88.8 males.
The median income for a household in the village is $69,519, and the median income for a family is $69,615. Males have a median income of ...