A permanent magnet is a ferromagnetic material that possesses permanent magnetic properties, even when it is not located within a magnetic field.
One end of the magnet is called the north pole, the other the south pole. North and south poles attract, and this attraction is inversely proportional to the square of the distance between the two poles. Like poles (north-north and south-south) repel.
Lines of flux are imaginary lines that indicate the direction of the magnetic field at a certain point. For magnets they can be made visible by placing a sheet of paper on the magnet and sprinkling some iron filings on the paper. The iron filings will cluster along the lines of flux, allowing you to see them.
In certain circumstances a permanent magnet can lose its magnetic properties. This can be caused by high temperature (see Curie temperature), a physical shock (impact) or exposure to external magnetic fields. Magnets supplied by Goudsmit are of such high quality that the loss of magnetic properties can be considered negligible, provided they are used within the specified operating parameters, which pertain to aspects such as temperature range and vicinity to external magnetic fields.
Permanent magnets were once made of steel, but we now have all sorts of alloys available that are better suited for this purpose.