Environment is the surrounding in which the organism lives. There are many biotic and abiotic factors on which the organism depends and without them the organism can survive. The biotic component refers to the living component of the environment while on the other hand, abiotic factor is the non-living component of the environment. All the organisms are depend on both living and non-living component of environment.
Figure 1 shows the past year prevalence of major depressive episode among U.S. adults aged 18 or older in 2017. An estimated 17.3 million adults in the United States had at least one major depressive episode. This number represented 7.1% of all U.S. adults.