Electromagnetism

Magnetism describes the invisible force that attracts or repels certain substances. This phenomenon was first observed in Ancient Greece when magnetite and its properties were discovered. This ore can attract small iron objects. Later, in the 11th century, these magnetic properties were used to make the first compasses.

Today, we know that iron is not the only element that has properties similar to those of magnetite. Cobalt, nickel and gadolinium can also act as magnets or be attracted to magnets.

In the early 19th century, scientists discovered a link between magnetism and electricity. Electrical currents can generate magnetic fields, and magnetic fields can generate electrical currents. They concluded that electricity and magnetism are two aspects of the same force: electromagnetism.

Magnetic phenomena were discovered and explained a long time ago. Naturally occurring magnetism was observed and described in Ancient Greece. Our knowledge has greatly improved since then, and these phenomena are now omnipresent in our daily lives, from magnets holding notes on the refrigerator to electromagnets used to lift heavy loads. Our understanding of magnetism developed in three stages:

Greek writings dating from 800 to 600 B.C.E. suggest that the first person to pick up a magnet and play with it was a child. This child supposedly attached the mysterious rock, magnetite  |(Fe_{3}O_{4}),| to the end of a stick to attract metallic objects. After this discovery, the Greeks began to study this stone.	Magnetite  (Source)
The Chinese also discovered the magnetic properties of magnetite, using it for divination. They were the first to find a practical use for magnetism by placing a spoon made of magnetite on a polished surface: the handle always pointed south.  This spoon and plate invention was put to use and named the south pointer.	Chinese compass (Source)

There are also fragments of legends about the magnetic effects of magnetite among the Egyptians and the Mayans. 

A fierce competition raged between France and England to make new discoveries about the link between electricity and magnetism.  Around 1820, François Arago (1786–1853) discovered that a loop of wire could induce magnetic behaviours on a piece of iron.	François Arago (Source)
A colleague, André-Marie Ampère (1775–1836), suggested that making several loops would increase the magnetic performance of François Arago’s loop. He also discovered that this electromagnet would influence the needle of a compass in the opposite way when the direction of the current was reversed. The electromagnet was born.	André-Marie Ampère (Source)
However, it was an Englishman, Michael Faraday (1791–1867), who invented the first system to create a continuous circular motion. This is how the first electric motor was invented.	Michael Faraday (Source)
In 1873, Scottish physicist James Clerk Maxwell published a series of equations known as Maxwell’s equations. He summarized the work done by other researchers into just a few equations, in which he clearly unified electricity and magnetism.	James Clerk Maxwell (Source)

Discoveries and inventions then followed in dramatic and rapid succession to become electricity and magnetism as we use them today.