This document provides an introduction and overview of GeoGebra, an interactive software for geometry, algebra, statistics and calculus. It was created by Markus Hohen Warter as part of his master's thesis in 2001 at the University of Salzburg, Austria. GeoGebra is free, open-source software that can be downloaded and used on computers, laptops, mobiles and other devices for teaching and learning mathematics. It has several advantages like being free, compatible with multiple platforms, and able to be used both online and offline.