This document provides an overview of brain-computer interfaces (BCI). It discusses the history and development of BCI, including early work using electrodes implanted in monkeys. The document outlines different approaches to BCI, including invasive, semi-invasive, and non-invasive methods. Applications mentioned include providing communication assistance and environmental control for disabled individuals, enhancing video games, and monitoring brain states. Several current BCI projects are also briefly described, and the conclusion discusses BCI's potential therapeutic benefits and role in human enhancement.