Homeostasis refers to the notion that the body monitors and maintains internal states, such as body temperature and energy supplies, at relatively constant levels. It is any process in any living organism which is responsible of maintaining stability in the body by adjusting or adapting to any changes in the outside conditions. For example, the human body would tend to maintain a temperature internally of about 98.6 degrees Fahrenheit regardless of what is the temperature outside the body. So, if the outside temperature is hotter, then certain process in the body would try its best to regulate the temperature inside and maintain the recommended level.
