Definition: parameter

(1) Any data value passed to a program by the user or by another program in order to configure the program for a particular purpose. A parameter may be anything; for example, a file name, a coordinate, a range of values, a money amount or a code of some kind. Parameters may be required as in parameter-driven software (see below) or they may be optional. Parameters are often entered as values following the program name when it is loaded. For example, in the DOS/Windows command dir /p, the /p is a parameter that modifies the Dir command to pause after every screenful. See parameter driven.

AI Data Parameters
Since the advent of ChatGPT and other AI systems, people increasingly hear about the huge number of data parameters used to train them. In this case, a parameter can be any data whatsoever, from words and sentences to a lengthy article or even an entire book. See AI training and ChatGPT.

(2) In programming, a parameter is any value passed to a subroutine or function for processing, and hundreds of parameters are used in today's graphical applications. For example, in the following C function, which creates the text window for the Windows application of this encyclopdia, there are 11 parameters passed to the CreateWindow routine. Some of the parameters call yet other functions for necessary information. Although many of the parameters that make up a call to a routine are defaults, programmers do have to determine new values and make changes from time to time. See default and parameter driven.

 hWndText = CreateWindow
 (
 "TextWClass",
 NULL,
 WS_CHILD|WS_BORDER|WS_VSCROLL|WS_TABSTOP,
 xChar*23+GetSystemMetrics(SM_CXVSCROLL)+8,
 yChar*4,
 Rect.right-Rect.left+1-xChar*23
    -2*GetSystemMetrics(SM_CXVSCROLL)+5,
 yChar*(Lines+1)+2,
 hWnd,
 IDC_TEXTLIST,
 (HANDLE)hInstance,
 NULL
 );

Generate a Text Window