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 are found in various environments, including soil, water, and the human gut, where they play a crucial role in regulating bacterial populations. Scientists study bacteriophages for their potential use in medicine, particularly in treating bacterial infections. This approach, known as phage therapy, offers an alternative to antibiotics, especially in cases where bacteria have developed resistance. Bacteriophages can target specific bacteria, minimizing damage to beneficial microbes.