In 1968 at the University of Illinois, David Cohen made scientific history when he measured a neuronal oscillation known as the alpha rhythm from the brains of four human volunteers. The measurement of the alpha rhythm was not in itself a breakthrough: the German psychiatrist, Hans Berger, had discovered the rhythm decades earlier during his first recordings of human electroencephalography (EEG). What was novel about Cohen's experiment was that it did not measure electrical potentials on the scalp as is the case for EEG. Instead, the measurements were made using a metal coil built to measure magnetic fields. Cohen had become the first person to measure the brain's magnetic field and in doing so had pioneered an entirely new method for measuring the brain's activity: magnetoencephalograpy (MEG).In the intervening decades MEG has grown from a highly specialised method practiced by a small number of researchers to a routine method of human neuroscience available at laboratories across the world. However, as the use of MEG has increased, so too has the number of people encountering MEG for the first time, and this has created a growing need for materials that aid the understanding of MEG for those with no prior experience.