• Evolution refers to the process by which populations change over time. This process explains the diversity of life on Earth and forms the basis of our scientific understanding of the natural world.
• It's important to note that evolution only pertains to heritable characteristics. These are traits passed down from parents to offspring. A simple definition to remember is, "Evolution is a change in the heritable characteristics of a population over time."

Example: Imagine a population of beetles. Some beetles are green, and some are brown. The color is a heritable characteristic. If the green beetles are better camouflaged in the environment and survive more frequently to reproduce, the beetle population will gradually become greener over generations. That's evolution!

• The engine that drives evolution is called natural selection, also known as Darwinism, named after Charles Darwin who popularized the concept.
• It works like this: individuals with traits that improve survival and reproduction are more likely to pass these beneficial traits to their offspring. Over time, these advantageous traits become more common within the population.

Example: Let's return to our beetle friends. If birds can see brown beetles more easily and eat them, the green beetles will survive and reproduce more. So, the 'green color' trait, being beneficial, gets naturally selected over generations.