The electroencephalogram (EEG) is a widely used noninvasive method for monitoring the brain. It is based upon placing metal electrodes on the scalp which measure the small electrical potentials that arise outside of the head due to neuronal action within the brain. Its key benefits compared to other brain imaging techniques are that it has a very high time resolution – able to track events within the brain with millisecond accuracy – and that it is in principle portable allowing real-world neuroimaging to be performed outside of clinical and lab environments. As a result it is a very widely used sensing modality for a range of health and wellbeing applications ranging from epilepsy diagnosis to emotionalmonitoring. The EEG is a very widely used technology for neuroimaging. It is unique amongst sensing methods in that it can monitor the brain portably, over a long period of time, and with a high time resolution for capturing rare and transient events. As a result it has seen substantial use in medical diagnoses and increasingly in out-of-the-lab brain monitoring.