Macroscopic brain sigals, e.g., the noninvasively measured scalp EEG/MEG, correlate with mental states, such as movement intentions. This opens a new communication channel for paralyzed patients as their intentions can be 'read' by computers and utilised for triggering technical devices. This entry-level tutorial will provide an intuitive introduction into the relevant brain anatomy and physiology and describe typical procedures as well as potential pitfalls when obtaining and analysing multichannel EEG/MEG data.