From OER in Education

Geogebra(tool) is a tool for modelling(ta) in geometry(topic). An alluring feature is that you can change parameters on pre-built models using a mouse. You can indeed create models pretty much by drawing on-screen. Remarkably this ‘dynamic geometry’ application, offers the great convenience of running in a browser, but can be downloaded to work offline on a desktop. Impressive and deservedly popular.