Answer: When your immune system encounters a harmful invader (antigen) for the second time, it reacts much faster and stronger. This is because it remembers the invader from the first encounter.Special memory cells, both B cells and T cells, recognize the invader quickly and multiply rapidly. The memory B cells turn into antibody-producing cells that attack the invader, while memory T cells help coordinate the response.This second response results in more antibodies being produced, which are better at fighting the invader. It also reinforces your immune memory, so you're better protected if you encounter the same invader in the future.