Texas Instruments TI-83 PLUS - Manual (Page 519)

TI-83 Plus Programming 516
Program Output
While
While performs a group of commands while condition is true. condition is
frequently a relational test (Chapter 2). condition is tested when While is
encountered. If condition is true (nonzero), the program executes a group
of commands . End signifies the end of the group. When condition is false
(zero), the program executes each command following End . While
instructions can be nested.
:While condition
: command (while condition is true)
: command (while condition is true)
:End
:
command