We all know that our immune response is what keeps our bodies safe. This process (actually, in humans, it’s processes) is when our body distinguishes from ‘self’ to ‘other’, attacking the ‘other’ to preclude their invasion of the whole body. The system gains complexity as it adapts to recognize various pathogens (invaders) more efficiently. This is called acquired immunity (immunological memory); it is one of the reasons we get vaccinated- our body learns to respond to this pathogen and similar types- which can take from 2 days to several weeks to fully develop. This secondary response is critical for our homeostasis, our ability to remain ‘self’ and not be overtaken by ‘others’.