What is meant by the term "magnetic field lines"? List two properties of magnetic field lines.

(N/A) magnetic field line is a path that would be followed by a hypothetical north pole if it were allowed to move freely in the magnetic field of another magnet.
Two properties of magnetic field lines are:
$(i)$ Two magnetic field lines never intersect each other.
$(ii)$ Outside the magnet, they travel from the north pole to the south pole, and inside the magnet, they travel from the south pole to the north pole.