In an electromagnet the magnetic field is created through electric current in a wire-wound coil and strengthened by a soft-iron core. As soon as you turn off the power, the soft-iron core loses its magnetisation.
A permanent magnet is made of ferromagnetic material, which is magnetised by a strong external magnetic field. The magnetically hard material that is used keeps part of its magnetisation after the external magnetic field is turned off.
The attraction between magnets is a little stronger than the repulsion. That is due to the alignment of the molecular magnets in the magnet. The attraction as well as the repulsion of magnets decrease significantly with increasing distance.
A magnet having a preferred direction of magnetic orientation, so that the magnetic characteristics are optimum in one preferred direction.
A magnet material whose magnetic properties are the same in any direction, and which can therefore be magnetized in any direction without loss of magnetic characteristics.
Remanence Br is a measurement for the magnetic induction or magnetic flux density that, after successful magnetisation, remains in the magnet. Simply said: the higher this value is, the "stronger" the magnet. T (Tesla) is used as the unit of measurement for magnetic induction and, respectively, magnetic flux density. The unit of measurement previously used was G (Gauss). 1 Tesla = 10 000 Gauss.