Poxviruses are a family of viruses known for causing diseases in humans and animals. They are large, complex viruses that can be seen under a light microscope. The most well-known poxvirus is the variola virus, which causes smallpox, a disease that has been eradicated since 1980 due to successful vaccination efforts. These viruses replicate in the cytoplasm of host cells and have a unique structure, including a double-stranded DNA genome. Other notable poxviruses include the vaccinia virus, used in the smallpox vaccine, and the monkeypox virus, which can cause illness in humans and is related to smallpox.