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 if the same pathogen invades again. Key components of the adaptive immune system include T cells and B cells. T cells help identify and destroy infected cells, while B cells produce antibodies that neutralize pathogens. This system is crucial for long-term immunity and is the basis for how vaccines work, training the immune system to recognize and combat specific threats.