Answer:
Natural selection is process that allow organism that has suitable attributes with its environment, to thrive (grow in population), to survive, and to pass its genetic information to the next generation (children, grand children).
Explanation:
For example: in an island, a male giraffe, and a female giraffe produce giraffe children with various attributes. Some giraffe children have short neck, and some have long neck.
Giraffe eats the leaves of Acacia tree, and Mimosa tree. Many acacia tree and tall mimosa tree in that island, are tall trees, so a giraffe that has long neck can reach that tall tree, eat the leaves, survive, and grow to adult stage.
A giraffe that has short neck, can only eat small quantity of leaves, then it suffers, can not grow, becomes skinny, and unable to compete with other giraffe finding its mate. It can't pass its genetic information to the next generation, and becomes extinct.
That's how natural selection, in above case, an island with a lot of tall acacia trees and mimosa trees <em>selects</em> giraffe with long neck to survive.
The next interesting follow up question would be how a male giraffe and a female giraffe produce various kind of giraffe children? The answer is a pair of chromosome become a single chromosome in giraffe sperm, and in a giraffe eggs. But that question and its answer are beyond the scope of the original question.
