What is a virus and how does it differ from bacteria?

Viruses are tiny particles that infect organisms such as animals, plants and humans often causing disease. They differ from bacteria because they cannot replicate on their own and require a ‘host’ such as a human to be able to multiply and spread – think of how a computer virus works – it gets into the system, it replicates, it causes damage and then spreads

Viruses cause symptoms of disease when they multiply inside the cells of the host, causing cell damage.