Let's start with what a magnet does. A magnet pulls on other magnets. It also pulls on some iron and steel things, such as pins and paper clips. Some stones are natural magnets. Every magnet has a north pole and a south pole. Opposite poles pull on each other. The same poles push each other away. A magnetic field is the area around a magnet where its force can be felt.

Now let's look at what makes a magnet. In a permanent magnet, tiny magnetic regions called domains line up in the same direction. Magnetism is caused by the motion of electric charges. An electric current creates a magnetic field. A permanent magnet loses its magnetism if it is heated enough.

Here is a rule to keep. Magnets are not for mouths or small children. Loose magnets can hurt children if they are swallowed. So can high-powered magnet sets. A child who swallows more than one has a problem. The magnets can pull together inside the body. That can cause serious damage. It is a calm rule and an easy one to follow.

Earth is a really big magnet. Its magnetic field begins in its core. The motion of electrically conducting iron in Earth's outer core makes electric currents. Those currents generate Earth's magnetic field. Invisible lines of force flow between its magnetic poles. These poles are not the same as its geographic North and South Poles.

Now let's see how people use Earth's field. A compass has a magnetized needle. The needle turns to line up with Earth's magnetic field. That is what makes a compass work. A lodestone compass was used in navigation as early as 1086. People have used a compass for hundreds of years to find their way.

Words to know

• domains: tiny magnet regions
• needle: compass pointer
• lodestone: natural magnet
• core: Earth's center