Bacteriophages are viruses that infect bacteria. By studying how these viruses interacted with bacteria, scientists were able to deduce the basic principles of viral replication, including:

* Attachment: Viruses attach to the surface of host cells.

* Entry: The viral genetic material enters the host cell.

* Replication: The viral genetic material is replicated using the host cell's machinery.

* Assembly: New viral particles are assembled from the replicated genetic material and proteins.

* Release: New viral particles are released from the host cell, often destroying the host cell in the process.

The study of bacteriophages paved the way for understanding how other viruses, including those that infect humans, reproduce.