Transcranial magnetic stimulation (TMS) is a technique introduced in the mid-1980s that uses a coil placed close to the head to generate a strong pulsed magnetic field that induces current flow in the outer layers of the brain. Depending on the stimulation parameters, TMS either increases or decreases the excitability of the affected nerve tissue, while the inhibitory effect can be so strong that one speaks of a temporary shutdown of the region (a so-called virtual lesion). Transcranial direct current stimulation (tDCS), in which a weak current acts on areas of the brain near the skull via electrodes attached to the scalp, has been known since the beginning of the 19th century and is much easier to use than TMS. Again, the excitation threshold of stimulated neurons is either increased or decreased depending on the selected polarity and electrode position. There is experimental evidence for both TMS and tDCS that they have the potential to improve a wide range of cognitive functions, from language skills, learning and memory to alertness and attention. The effects are mostly minor to moderate and usually do not last long.