What is GeoGebra?
The Basics
GeoGebra is dynamic mathematics software for schools that joins geometry,
algebra, statistics and calculus through graphing and spreadsheets. It was developed by a PhD student for a dissertation and as such is free and always will be. Development teams work under grants to maintain and enhance the software.
GeoGebra can be downloaded for free (from www.geogebra.org/download) to work on the "desktop." This version is more reliable, powerful, and easy to use. There is also a web-based application that we are using today for convenience. It can be slow and quirky sometimes but is still very functional.
On the one hand, GeoGebra is an interactive geometry system. You can do
constructions with points, vectors, segments, lines, polygons and conic sections as well as functions while changing them dynamically afterwards.
On the other hand, equations and coordinates can be entered directly. Thus,
GeoGebra has the ability to deal with variables for numbers, vectors and points.
It finds derivatives and integrals of functions and offers commands like
Root or Vertex.
User Interface - The Six Views
GeoGebra provides different Views for mathematical objects:
Each View offers its own Toolbar that contains a selection of Tools and range of Commands as well as Predefined Functions and Operators that allow you to create dynamic constructions with different representations of mathematical objects.
 Algebra View |  Graphics View |  Spreadsheet View |
 CAS View |  3D Graphics View |  Probability View |