The adaptive immune system is a specialized part of the body's defense mechanism that develops a targeted response to specific pathogens, such as bacteria and viruses. Unlike the innate immune system, which provides immediate but general protection, the adaptive immune system learns and remembers past infections. This allows it to respond more effectively upon subsequent exposures to the same pathogen. Key components of the adaptive immune system include B cells and T cells. B cells produce antibodies that neutralize pathogens, while T cells help destroy infected cells and coordinate the immune response. This system is crucial for long-term immunity and is the basis for how vaccines work.