The brain–computer interface (BCI) provides users with the possibility of sending messages and commands to the external world without using their muscles, thus enabling communication to occur independent of movement. Such a possibility is of utmost importance for paralyzed patients who may otherwise lose their ability to communicate. Enhanced methodology and the development of faster computers have substantially improved applications and offer new possibilities in this field. To date, there have been over 20 BCI research groups working on different approaches. In this paper, we review our studies of BCI based on electric and metabolic activity of the brain.