Here's a breakdown:

* Variation: Individuals within a species have different traits (e.g., beak size, fur color).

* Selection: The environment presents challenges (e.g., food scarcity, predators).

* Survival and Reproduction: Individuals with traits better suited to the environment are more likely to survive and reproduce.

* Inheritance: The advantageous traits are passed on to offspring, leading to a gradual change in the population over time.

In essence, natural selection favors traits that increase an organism's chances of survival and reproduction in a given environment.