Magnets are surrounded by magnetic fields. A magnetic field can be thought of as consisting of lines of force. The forces of magnetic attraction and repulsion move along the lines of force. The magnets below are on a virtual surface containing iron filings.

Click on S or N to change the polarity of the magnets.

The iron filings line up along the magnetic field lines of the magnets. Note the pattern of the field lines when unlike poles are placed opposite each other. Unlike poles attract each other. Note the difference in the pattern of field lines when like poles are placed opposite each other. Like poles repel each other.