The diagram below shows the magnetic field lines around a magnetised bar magnet. The density of the field lines shows the strength of the magnetic field. The density is highest by the N and S pole, so this is where the field is strongest.

This diagram shows where the real magnet would be in the diagram. You cannot directly see the magnetic field lines.

As stated earlier, the field is strongest where the density of field lines is highest (by the N and S pole). The field is weak where the field lines are less dense.

The diagram below indicates the strongest areas of the magnetic field and some weaker areas: