Definition: install program

Also called a "setup program" or "installer," an install program is software that prepares an application (software package) to run in the computer. Unless the app is a single utility program, it is made up of many files that are often stored in several levels of folders in the user's computer. In the Mac, the user never sees more than a single file, which is actually a compressed archive that expands into many folders and dozens or hundreds of files (see APP file). In a Windows PC, all related files and folders are typically visible. See utility program.

To save space, application files are compressed into one or more "archived" files. If the installation comes on a CD or DVD, there is room on the optical disc for multiple files. However, when coming from the Web, the install program creation system compresses the files and packages them into a single executable program so that there is only one file to download. Another approach on the Web for very large applications is to download a program that subsequently downloads multiple files, all of which happens automatically.

Whether from the Web or a physical medium, users run the install program to decompress the files and save them in a specific folder hierarchy in their storage drive. For Windows apps, the install program may make entries in the Windows Registry, which is a database of configuration data (see Registry).

Like a Self-Extracting Archive
An install program is similar to a self-extracting archive, which is a collection of compressed files packaged as one executable program. When a self-extracting archive is run, it creates a folder hierarchy and decompresses the files into the appropriate folders.

However, an install program does much more. For example, it can check the computer's configuration and install different files or create folders in different locations. It can also offer the developer customization options. In addition, it is customary for the install program to include an uninstall program in the application folder so that the entire application can be easily removed (see uninstall).

Installation Systems
Developers can generally choose from a variety of both free and paid installation packages that compress the files and create the install program. The dialogs users see may be standard or customizable, and a scripting language may be available for further customization. In the Linux world, packaging systems differ greatly from Mac and Windows (see package manager).

Also for Hardware
Install programs are also used to attach a new peripheral device to the computer. The install program may add the device's software driver to the operating system. If a controller card was plugged into the computer, the install program may set parameters in an updatable flash memory or EEPROM chip on the card itself. See silent install, unattended install, uninstall, how to install a program and BIOS setup.

Install Files and Folders

The primary purpose of an install program is to create a group of files and folders on the user's computer. In this Windows example, SetupABC.exe is a single file suitable for downloading from the Web.