As we live our lives, we use resources to heat and light our homes, travel and even to produce our food.
When power stations create that power for us to use, they produce gases as waste. One of them is called carbon dioxide, and a number of experts are convinced it plays a big part in climate change.
Reducing the amount of carbon dioxide people - and countries - around the world use up is seen as a key way to reduce climate change.
To help individuals reduce the amount of carbon dioxide they are responsible for, a way of measuring it was created.
It's called a carbon footprint, and the more a person produces, the larger their carbon footprint is said to be.
It's not just about electricity and gas though.
Someone who goes on lots of plane journeys or drives a car everywhere would have a much bigger footprint than someone who doesn't.
That's because planes and other vehicles also produce carbon dioxide.
That means that if you eat food from your back garden your footprint won't get much bigger. If you eat food flown to the UK from around the world, then your carbon footprint will be much bigger.
Similarly, if you get a bus to school, that's better than being driven on your own, because the gases the bus gives off when driving are spread across lots of people.
Some things that make a small carbon footprint
Walk/Cycle to school
Read books for fun
Eat food grown in the garden
Go on holiday in the UK
Some things that make a big carbon footprint
Driven to school
Play games console/watch TV for fun
Eat food flown to the UK
Fly away to far-off countries on holiday