Transcranial Magnetic Stimulation (TMS) and Transcranial Direct Current Stimulation (TDCS) are both non-invasive methods for stimulating parts of the brain. TMS and TDCS are active neuro devices, in the sense that they change the firing rates and activity levels of neurons, and groups of neurons in the brain. Major differences between TMS and TDCS are described below.

Transcranial magnetic stimulation (TMS) is a noninvasive method to cause depolarization or hyperpolarization in the neurons of the brain. TMS uses electromagnetic induction to induce weak electric currents using a rapidly changing magnetic field; this can cause activity in specific or general parts of the brain with little discomfort, allowing for study of the brain's functioning and interconnections.
Transcranial direct current stimulation (tDCS) is a noninvasive form of neurostimulation which uses constant, low current delivered directly to the brain area of interest via small electrodes. Tests on healthy adults demonstrated that tDCS can increase cognitive performance on a variety of tasks, depending on the area of the brain being stimulated. It has been utilized to enhance language and mathematical ability, attention, problem solving, memory, and coordination