The term "golem" is largely misunderstood due in part to the difference between popular uses of the moniker in different mythologies.
In its original and primary meaning, a golem is a humanoid creature made of some sort of inanimate mineral and brought to life through magic. A person with the right skills could build a "person" out of sand, dirt, clay, or stone, and then magically animate and controlling the creature. Golems can be brought to life through various magical methods, but the most common is either etching a magic word into their foreheads or writing a magic word on a piece of paper and putting it in their mouths.
An important note about golems is that they do not have a mind of their own. They are quite like robots in the sense that they can't think for themselves, they can only follow commands. It is also important to remember that golems take their orders literally. Their controllers must be very specific so the golem doesn't cause more trouble than it helps.