In computing, downgrading refers to reverting software (or hardware) back to an older version; downgrade is the opposite of upgrade

Upgrade

The term upgrade refers to the replacement of a product with a newer version of the same product. It is most often used in computing and consumer electronics, generally meaning a replacement of hardware, software or firmware with a newer or better version, in order to bring the system up to date...

. Often, complex programs may need to be downgraded to remove unused or bug

Software bug

A software bug is the common term used to describe an error, flaw, mistake, failure, or fault in a computer program or system that produces an incorrect or unexpected result, or causes it to behave in unintended ways. Most bugs arise from mistakes and errors made by people in either a program's...

ged features, and to increase speed and/or ease of use. The same can occur with machine

Machine

A machine manages power to accomplish a task, examples include, a mechanical system, a computing system, an electronic system, and a molecular machine. In common usage, the meaning is that of a device having parts that perform or assist in performing any type of work...

ry.

An example of a downgraded program is Gmax

Gmax

Gmax is a 3D modeling application based on Autodesk's 3ds Max application used by professional computer graphics artists. Whereas 3ds Max is a comprehensive modeling, animation, and rendering package with some secondary post-production and compositing features, Gmax is much more limited due to its...

, a downgraded version of 3ds max used by professional computer graphics artists, free to download and simplified for ease of use.

The term "downgrade" became especially popularized during the days of Windows Vista

Windows Vista

Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...

, with users wanting to return to, or "downgrade" to (with some even calling it an "upgrade") Windows XP

Windows XP

Windows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base...

due to Vista's performance and familiarity issues.