Glad to present the chapter I wrote for the Book entitled *Machine learning for brain diseases*. This chapter aims at providing an overview of the electroencephalography and the magnetoencephalography domains. A preliminary version is available [here](https://hal.inria.fr/hal-03604421), and the code used to plot the figures and to propose some insights on M/EEG processing is available [here](https://github.com/mccorsi/ML-for-Brain-Disorders_MEEG).