A bacteriophage is a type of virus that specifically infects and replicates within bacteria. These viruses are composed of genetic material, either DNA or RNA, surrounded by a protein coat. Bacteriophages attach to bacterial cells, inject their genetic material, and hijack the bacterial machinery to produce new virus particles, often leading to the destruction of the host cell. Bacteriophages are important in various fields, including medicine and biotechnology. They can be used as a treatment for bacterial infections, especially those resistant to antibiotics. Additionally, researchers explore their potential in food safety and as tools for genetic engineering.