Any type of stress occurs amid ongoing adaptation to the environment when the body can produce a marked imbalance between environmental demands and possibilities of the individual real response. Adaptation involves preserving the integrity of the organism that is constantly threatened by stress agents of all kinds. In addition, adaptation involves a dynamic balance with the environment. Stress occurs when this balance is disturbed adaptation. This disturbance is reversible. Stress is a heavy imbalance between perceived subjectively by the individual organism and environment requirements and possibilities of individual response. Depending on the nature of stress, stress can be mentally, physically, chemically and biologically. Depending on the number of people affected, stress can be individually or collectively.