This document provides an overview of brain-computer interfaces (BCI). It begins with introducing BCI and explaining that it allows direct communication between the brain and external devices. It then covers the history of BCI, how it works using EEG signals, different BCI approaches (invasive, partially invasive, non-invasive), and applications like controlling prosthetics. Advantages include direct brain communication, while disadvantages include risks, training requirements, and costs. Examples of future projects are provided like controlling robots and games just by thinking. In conclusion, BCI allows thought-based control of devices and has many potential future applications.