The theory of evolution says that living things change over time, and that all species are related through common ancestors.

In simple terms:

- **Individuals are born with variation**: no two organisms are exactly alike.
- **Some variations help survival and reproduction** in a given environment.
- **Those helpful traits tend to become more common** over many generations.
- Over very long periods of time, these gradual changes can lead to **new species**.

This process is mainly explained by **natural selection**, a key part of evolution.

Evolution also says that:
- humans and other animals share ancient ancestors,
- species are not fixed forever,
- and the diversity of life on Earth developed over millions of years.

If you want, I can also explain:
1. evolution in one sentence,  
2. how natural selection works, or  
3. common misunderstandings about evolution.
