Natural selection follows from three principles, the first being that most characteristics are:

1. Darwin argued natural selection was an inevitable outcome of three principles operating in nature. 2. First, most characteristics of organisms are inherited, or passed from parent to offspring. 3. Second, more offspring are produced than are able to survive, so resources are limited. 4. Third, offspring vary among each other and those variations are inherited. _Source: OpenStax Biology for AP(R) Courses (CC BY 4.0), Ch 18 'Evolution and the Origin of Species', sections 18.1-18.3_