Final answer:
Viruses have genomes made of either DNA or RNA, which can be either single- or double-stranded and may be segmented. This variability in genomic structure contributes to the evolutionary capability of viruses.
Step-by-step explanation:
Viruses can contain either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) as their genetic material, but not both. This sets them apart from most living organisms, which typically use DNA. The viral genome, which is the total genetic content of the virus, is usually small and efficient, carrying only the genes that code for proteins the host cell does not provide.
Whether a virus contains DNA or RNA, the genetic material may be single-stranded or double-stranded and may come in linear or circular forms. Some viruses have their genomes divided into several segments, which can lead to high variability and evolution, as seen with the segmented RNA genome of the influenza virus.