The TI-83 series is a series of graphing calculators manufactured by Texas Instruments.
The TI-83 Plus
TI-83 Plus Silver Edition
A graphing calculator is a handheld computer that is capable of plotting graphs, solving simultaneous equations, and performing other tasks with variables. Most popular graphing calculators are programmable calculators, allowing the user to create customized programs, typically for scientific, engineering or education applications. They have large screens that display several lines of text and calculations.
A typical graphing calculator by Texas Instruments
Casio fx-7000G; The world's first graphing calculator
Graphing calculators are sometimes used for gaming.
TI-89 Titanium, capable of doing Symbolic Manipulation, Computer Algebra System (CAS)