Here's a breakdown:

* Natural Selection: The process by which organisms better adapted to their environment tend to survive and reproduce more successfully. This means that traits which make an organism better suited to survive and reproduce in its environment are more likely to be passed on to the next generation.

* Evolution: The gradual change in the genetic makeup of a population over time. This change can be driven by various factors, including natural selection.

In short, natural selection is the mechanism that drives evolution. It's a fundamental principle in biology that explains the diversity of life on Earth.

Here's a simple example:

Imagine a population of rabbits living in a forest. Some rabbits have brown fur and some have white fur. If the forest is full of brown trees, the brown rabbits will be better camouflaged and less likely to be eaten by predators. This means they are more likely to survive and reproduce, passing on their genes for brown fur to their offspring. Over time, the population will have more brown rabbits and fewer white rabbits. This is evolution by natural selection.

Here are some other key results of natural selection:

* Adaptation: Organisms become better suited to their environment over time.

* Speciation: New species can arise through natural selection.

* Extinction: Species that are not well-adapted to their environment may become extinct.

It's important to note that natural selection is not a goal-oriented process. It does not work towards a specific "perfect" organism. Instead, it simply favors traits that increase survival and reproduction in a particular environment.