Our latest unit in Physics was learning about magnetism. A magnetic field occurs when charged particles are moving. According to greek legend magnetism was discovered by a Shepard in a field as he suddenly felt a force of attraction coming from the ground as he wore shoes with iron on the bottom. The substance he found later became known as magnetite, after the place it was found, Magnesia. Another common magnetic substance that was well known was lodestone. This was used in ancient China by the first emperor to protect his palace. Huge blocks of lodestone were placed outside the entrance. This was meant to attract soldiers in armor so they were prevented from entering the village. In ancient Egypt magnets were used for entertainment by doing (non) magic tricks. They would place objects above a magnet so that they would repel so the object would seem to be floating in mid-air.
It wasn't until the 1500's that magnetism was scientifically investigated by William Gilbert who discovered that the earth itself is a magnet with a magnetic north pole and south pole. Not too much later came Friedrich Gauss and Charles Coloumb, where our understanding of magnetism became less of a mystery. In 1861 James Clerk Maxwell used equations to relate magnetism and electricity.