What is a cycle?
A cycle is a set of steps that keeps repeating, with no true beginning or end.
Think about the seasons: spring, summer, autumn, winter — and then spring again. The steps repeat over and over. That is a cycle.
A cycle has two important features:
- The steps happen in the same order each time.
- It repeats — when the last step finishes, the first one begins again.
Because a cycle goes round and round, there is no real start or end. You can join in at any point.
Cycles matter a lot in science. The Earth does not get fresh deliveries of water or nutrients from space. Instead, it reuses the same materials again and again. A cycle is nature's way of recycling.
The most important cycle you will study now is the water cycle — the journey water takes between the sea, the sky and the land. Later you will meet other cycles too, all built on the same idea: materials being used, returned and used again.
- A cycle is a repeating series of steps.
- The steps always happen in the same order.
- A cycle has no true start or end — it goes round and round.
- Cycles let the Earth reuse the same materials again and again.