A bacteriophage, or phage for short, is a virus that infects bacteria. Like other types of viruses, bacteriophages vary a lot in their shape and genetic material.
Microorganisms are minute organisms that are invisible to the naked eye. It can be grouped into five major types: Viruses, Bacteria, Archaea, Fungi, and Protists.
So, A bacteriophage is a microorganism.