DTaP is a combination vaccine that protects against three serious diseases: diphtheria, tetanus, and pertussis (whooping cough). It is typically given to children in a series of five doses, starting at two months of age. The vaccine helps the immune system recognize and fight these infections. Diphtheria is a bacterial infection that can cause severe throat swelling, while tetanus is caused by bacteria that enter the body through wounds, leading to muscle stiffness. Pertussis is a highly contagious respiratory illness. Vaccination with DTaP is crucial for preventing these diseases and protecting public health.