In the ancient times, it was a known fact that pieces of iron metal from the Magnesia region in Little Asia had magnetic qualities. It is after this region that the name 'Magnet' was awarded to everything that portrayed this phenomenon of magnetism. 

    Magnets come in different shapes and sizes. For example: rod magnets, needle magnets, horseshoe-shaped magnets, semi-circular magnets, etc.

    A magnet consists of two poles, a North pole and a South pole. These two poles are inseparable; one cannot exist without the other. If one divides a magnet into units then each unit will contain its own north and south poles. It is these units that assert their influence the most i.e. the poles have the strongest magnetic force.

    Magnetic field is the space around a magnet in which a different magnet is affected by the force field, from the first. The strength of a magnetic field depends on the amount of force-lines per unit area. This unit strength is measured in Gauss, Oersteds or Tesla, terms made after the names of the physicist who worked out these measures.

   The earth is also considered as a gigantic magnet wherein its magnetic field-strength lies at around 0.3-0.47 Gauss on the surface. The earth is surrounded by an atmosphere which consists of different electrical fields. As the earth possesses magnetic materials, these currents  produce a magnetic earth field. Earth's magnetism changes according to daily and yearly fluctuations. These fluctuations are brought about mainly due to changes in the sun's magnetic field. The sun's rays affect the top layers of the atmosphere causing changes in the earth’s magnetic field, which in turn affects many biological processes in human beings. 

     Apart from the earth and the sun, other planets like the moon, stars, etc. also have magnetic fields.