GeoGebra is free, multi-platform dynamic mathematics software that joins geometry, algebra and calculus.

What does multi-platform mean?
Multi-platform means it works on both PCs and MACs.

What does dynamic mean?
Dynamic means that the user can interact with the computer.

Where does the name GeoGebra come from?
Take the first three letters of GEOmetry and put it together with the last five letters of AlGEBRA:

How is it pronounced?
Dr. Fisher pronounces it like Algebra, except with a ‘Geo’ at the beginning. (Both G's are soft.)

Here are names that will be used for various GeoGebra elements in subsequent tutorials and worksheets.
(Some of these names are ever-so-slightly different than the names that GeoGebra uses.)

GEOGEBRA WINDOW:
TOOLBAR:
MOVE tool:
POINT tool:
LINE tool:
SEGMENT tool:	(in the pull-down menu beneath the LINE tool)
PERPENDICULAR LINE tool:
PARALLEL LINE tool:	(in the pull-down menu beneath the PERPENDICULAR LINE tool)
POLYGON tool:
CIRCLE tool:
ANGLE tool:
REFLECT ABOUT LINE tool:
SLIDER tool:
MOVE DRAWING PAD tool:
MENU:	Notation like ‘Options-Angle unit-Radians’ is used to mean the following: Click on   Options   in the MENU. In the sub-menu that appears, click on   Angle unit . In the sub-menu that appears, click on   Radians .
ALGEBRA WINDOW:
GEOMETRY WINDOW (or DRAWING PAD):
INPUT FIELD:
DEGREE MENU:	(This menu contains the degree symbol, constants, functions, and relations. I call it the ‘degree menu’ because that symbol was originally what showed.)
GREEK LETTER MENU:
COMMAND MENU: