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. Gravity has no poles, because the gravity from every part just adds together. Magnets are different. Every magnet has a north pole and a south pole. Opposite poles pull on each other. The same poles push each other away. Here is a rule to keep. Magnets are not for mouths or small children. Loose magnets can hurt children if they are swallowed. If a child swallows more than one, the magnets can pull together inside the body and cause serious damage.

Now let's look inside magnets. A magnetic field is the area around a magnet where its force can be felt. Two kinds of magnets exist: permanent and temporary. In a permanent magnet, tiny magnetic regions called domains line up in the same direction. A permanent magnet loses its magnetism if it is heated enough. Magnetism is caused by the motion of electric charges. An electric current creates a magnetic field.

Now let's see how people explored that link. In 1820 Hans Christian Ørsted's discovery showed that electricity and magnetism are related. Joseph Henry, following Ørsted and Ampère, introduced the electromagnet. William Sturgeon built the first practical electromagnet. It was strong enough to support 20 times its own weight. Michael Faraday discovered electromagnetically induced currents in 1831. A changing magnetic field near a conductor can create an electric current in the conductor. The current depends on the rate at which the field changes.

Electromagnets are not permanent, but they can be far stronger than the strongest permanent magnet. Strong magnets can even hold up a train. A Maglev is a kind of train. In a Maglev train, magnets suspend the car above a U-shaped concrete guideway. The magnets repel one another when matching poles face each other, just as ordinary magnets do. In a Maglev system the powered guideway drives the train.

Now let's look at Earth itself. 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 poles. The Sun sends out a flow of charged particles called the solar wind. Earth is also surrounded by a large magnetic shield called a magnetosphere. It protects us from harmful charged particles in space.

Now let's see how people find their way. A compass has a magnetized needle that turns to line up with Earth's magnetic field. That is what makes a compass work. People have used compasses for hundreds of years to find their way. A lodestone compass was used in navigation as early as 1086. Magnetic declination is the angle between magnetic north and true north. It is positive when the angle is east of true north and negative when west. As of November 2026, Earth's magnetic north pole is moving. This gradual shift must be regularly accounted for in navigation.

Words to know

• electromagnet: magnet from current
• domains: tiny magnet regions
• declination: compass angle
• magnetosphere: magnetic shield