Electricity and magnetism are very closely linked. When electricity flows through a wire a magnetic current is formed. when a wire is moved through a magnetic field an electric current is formed.  This concept can be used to create an electromagnet.  these can be useful as they can act as a magnet that can be turned on and off. to increase the strength of an electromagnet you can either add more coils of wire, use a higher current or add an iron core. Electromagnets can be used in electronic security bolts as well as electric bells.

This video gives a good overview of the electromagnetic spectrum.