The highest number of individuals of a particular population that an ecosystem can support is called as the carrying capacity. The population depends on the environment for the basic necessities like the food, water, habitat, etc. the maximum population that can be sufficiently supported by all these factors by the ecosystem is called the carrying capacity. It is the point at which the average growth rate of any population becomes zero.
For better understanding, let us consider the hypothetical logistic growth curve of spotted deer population. The horizontal red line passing through the curve corresponds to a number on y - axis. This number refers to the carrying capacity. Here, carrying number is 76 million. This indicates that an environment considered here can support highest of 76 million spotted deer.