A prophage is a form of a bacteriophage (a virus that infects bacteria) that has integrated its genetic material into the host bacterium's chromosome. In this latent state, the viral DNA is replicated along with the host's DNA during cell division, allowing it to pass on to daughter cells without destroying the host. Prophages can remain dormant until specific conditions trigger their activation, leading to the production of new viral particles and the lysis of the host cell. This process plays a significant role in bacterial evolution and gene transfer.