Magnetic polarity

A magnetic field has a direction at any given point in the space near a current carrying wire or a permanent magnet. The flux lines run parallel with direction of field. A magnetic field is considered to begin at north magnetic pole, and to terminate at south magnetic pole. In the case of permanent magnet, it is obvious where these poles exists.

Figure--   Pattern of magnetic flux lines around a current-carrying wire.

With a current-carrying wire, the magnetic field just goes around and around endlessly, like a dog  chasing the tail of its own.

A charged electric particle, such as a proton, moving in space, is a monopole, and the electric flux lines around it are not closed. A positive charge does not have to be mated with the negative charge. The electric flux lines around any stationary, charged particle run outward in all the directions for the infinite distance.

 
Figure--            Electric flux lines around a monopole charge.

But a magnetic field is different; all magnetic flux lines are the closed loops. With permanent magnets, there is always a starting point and an ending point. Around current carrying wire, loops are circles. This can be seen in experiments with the iron filings on paper. The magnetic flux lines never run into infinity and never are a magnetic pole found without an accompanying, opposite pole.