A lighter is a small device that helps you make fire easily. It is used to light candles, cigarettes, or even a campfire. You hold the lighter in your hand and press a button or flip a switch to create a little flame.
The lighter has a tiny gas tank inside which is filled with a special gas called butane. When you press the button to light it, the butane gas comes out of a tiny hole and mixes with air. This creates a hot, glowing flame.
The flame is hot enough to burn things, but it won't hurt you if you use it carefully. You should always have an adult help you use a lighter, and never use it near anything that could catch on fire, like paper or curtains.
There are many kinds of lighters, but they all work in basically the same way - they help you start a little fire whenever you need it.