The document discusses different types of viruses and their replication cycles. It compares bacteriophages to polyhedral viruses and shows their structures. The general virus replication cycle is outlined in 5 steps: 1) attachment to a host cell, 2) entry into the host cell, 3) uncoating of the virus genome, 4) using the host cell to synthesize new viral components and assemble new virus particles, and 5) exiting the host cell. Images are provided to illustrate different viruses and stages of the replication cycle.