Every day, we are exposed to a wide array of potentially harmful microorganisms — such as colds, the flu and even COVID. But our immune system — a network of intricate pathways within our body — helps protect us against these microorganisms and other potential diseases. Essentially, it recognizes foreign invaders, such as viruses and bacteria, and takes immediate action to defend us.
Humans have two types of immunity: innate and adaptive. Innate immunity is the body's first line of defense, primarily consisting of physical barriers (such as skin) and secretions (including mucus, stomach acid and enzymes in saliva and sweat that prevent microorganisms from getting inside the body). It also consists of cells that attack all foreign invaders entering the body.
