Refer to figures.
Magnetism is an invisible force characterized by the ability of an object to attract certain metallic substances, primarily those containing iron (ferric materials).

A magnet is a ferrous object, often a bar of soft iron, through which lines of magnetic force flow. These lines extend around the magnet, forming a magnetic field—just like the Earth, which itself acts as a magnet. These lines of force are referred to as the magnetic flux.

When sprinkled with iron filings, the magnet reveals these "lines of force," which converge near the ends of the magnet. These areas are called the poles of the magnet, where its magnetic properties are most concentrated. Every magnet, regardless of its shape, has two poles.

Importantly, a single magnetic pole cannot exist. If a magnet is divided, each resulting piece will have its own two poles.

A bar magnet or compass needle suspended freely in the Earth’s magnetic field aligns itself roughly along the north-south axis. The end that points toward the north is called the north-seeking or red pole, while the opposite end is the south-seeking or blue pole.

By convention, magnetic lines of force emerge from the red pole and return to the blue pole.

When two bar magnets are aligned so that the blue poles face each other, a repulsive force is felt. The same repulsion occurs if the red poles are aligned. However, when the blue pole of one magnet is brought near the red pole of the other, they attract. This follows the fundamental rule of magnetism:

• Like poles repel
• Unlike poles attract