What is survival of the fittest and natural selection mean?

"Survival of the fittest" is a phrase that originated from Darwinian evolutionary theory as a way of describing the mechanism of natural

Explanation:

SUBSTANCE: Material composed of only one kind of matter throughout (same atoms or same molecules) ELEMENT: A substance that cannot be decomposed (broken down) into simpler substances by ordinary chemical means. Examples: gold, iron, carbon, hydrogen, oxygen, nitrogen.