<human>: Can you explain the difference between a virus and a bacterium?
<bot>: A virus is a small infectious agent that replicates only inside living cells. It can cause disease by inserting its genetic material into the DNA of an infected cell, which then uses it to produce more viruses. Bacteria are larger than viruses and can reproduce on their own without needing a host cell. They are also capable of producing toxins that can harm or kill other organisms.