Antibiotic resistance is caused by the overuse and misuse of antibiotics. When antibiotics are used to treat bacterial infections, they kill off the susceptible bacteria, but some bacteria may survive due to genetic mutations or the presence of resistance genes. These surviving bacteria can then reproduce and pass on their resistance genes to their offspring, which can lead to the development of antibiotic-resistant strains of bacteria. Over time, the widespread use of antibiotics can create an environment in which antibiotic-resistant bacteria thrive, making infections more difficult to treat and posing a serious public health threat.