How is the direction of a magnetic field defined at any location?

The direction of a magnetic field is by convention, the direction towards which the northpole of a compass needle points when placed under the influence of the magnetic field at any location.

Explanation:

A Magnetic field is a vectorial force field.

As such, the direction of such a field is very important when describing it.

The direction of a magnetic field is by convention, the direction towards which the northpole of a compass needle points when placed under the influence of the magnetic field at any location.

The direction of a magnetic field may be further described using magnetic field lines .

PS: An important feature of magnets is that like poles repel and unlike poles attract. Just an additional detail.

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