The fire triangle is like a magic spell that explains how fires happen. Three things must be present for a fire to start: heat, fuel, and oxygen.
Heat is like a spark, it can come from matches, lighters, or even a hot stove.
Fuel is like a yummy treat for the fire, it can be wood, paper, gasoline or anything that is flammable.
Oxygen is like the air we breathe. Without air, we cannot live and without oxygen, the fire cannot burn.
If all these three things come together, the fire will start and keep on burning until one of them is taken away. Imagine making a cake, you need flour, sugar, and eggs. Similarly, a fire needs heat, fuel, and oxygen.
So always remember, never play with matches or lighters, and always be careful around things that can catch fire because once they start, they can be very dangerous.