Other sections of this site deal with where EMFs come from and what they do. This section deals with the more fundamental question: what are EMFs?

Electric and magnetic fields (often referred to as EMFs) and the electromagnetic forces they represent are an essential part of the physical world and of life itself. Their sources are the charged fundamental particles of matter (principally electrons and protons).

Electric and magnetic fields occur naturally within the body in association with nerve and muscle activity. We also experience the natural magnetic field of the Earth (to which a magnetic compass responds) and natural electric fields in the atmosphere.  The fields this site is concerned with are produced by currents and voltages in the electric power system, but you can see their presence by the effect of the magnetic field on iron filings just as with a bar magnet.

• Electric fields are produced by voltage.
• Magnetic fields are produced by current.
• Some people use the terminology "electromagnetic fields" and there's also the terminology "magnetic flux density"
• EMFs are not the same thing as radiation
• Magnetic fields are often elliptically polarised
• Electric and magnetic fields add together in a special way because of being vectors

For information on where EMFs come from, see sources of EMFs

We have also provided a guide to the terminology used when talking about EMFs.

This site deals mainly with power-frequency EMFs (also known as extremely low frequency or ELF EMFs). But we give some links to information on radiofrequencies and a summary of the differences.  We also give some information on DC or static fields.