Simple Definition:

Homeostasis is the process by which living organisms maintain a stable internal conditions despite changes in external conditions [conditions outside of the body]. This balance is achieved through continuous adjustments made by the body’s systems, including the nervous, endocrine [the glands and organs that make hormones and release them into the blood stream], and immune systems. For instance, when the body temperature increases due to hot weather, the body responds by sweating to cool down. Another example is blood sugar. Our bodies keep our blood sugar levels balanced. When we eat, our body releases insulin to lower high blood sugar levels. If blood sugar gets too low, it releases glucagon [a liquid that helps your body to use the food that you eat] to raise it back up.

Very Simple Definition:

Homeostasis is the body’s way of keeping everything in balance, like a thermostat that regulates temperature in a room. For example, when you get shivery in the cold, or sweat in the summer, that’s your body trying to maintain homeostasis.