Bacteriophages, also known as phages, specifically attack bacteria. They are viruses that can only replicate inside bacterial cells.

Here's a breakdown:

* Host Specificity: Phages are highly specific in their host range. This means that a particular phage will only infect a specific type of bacteria or a small group of closely related bacteria.

* Types of Bacteria: Phages can infect various types of bacteria, including:

* Gram-positive bacteria: These have a thick layer of peptidoglycan in their cell walls (e.g., *Staphylococcus*, *Streptococcus*).

* Gram-negative bacteria: These have a thinner layer of peptidoglycan and an outer membrane (e.g., *Escherichia coli*, *Salmonella*).

* Diversity: There is a vast diversity of phages, and new phages are still being discovered. This diversity allows phages to target a wide range of bacteria.

In summary, bacteriophages exclusively attack bacteria, showing a high degree of host specificity.