What is a virus that infects bacteria called?

A virus that infects bacteria is called a bacteriophage (or simply phage). Bacteriophages specifically target bacteria and inject their genetic material into the bacterial cell, hijacking the host’s machinery to replicate the phage. The newly formed phages are then released, often destroying the host cell in the process. Bacteriophages can be used in phage therapy to treat bacterial infections, especially those resistant to antibiotics.