What is "white box"

White box may refer to:

• White-box testing, a specification conformance test
• White box (computer hardware), a personal computer assembled from off-the-shelf parts
• White box (software engineering), a subsystem whose internals can be viewed
• White-box cryptography, a cryptographic system designed to be secure even when its internals are viewed.
• White Box Enterprise Linux, a Linux distribution similar to Red Hat Enterprise Linux
• WHITEbox, an album set by Sunn O)))
• "White Box", the title of a special Christmas episode in Series 5 of Absolutely Fabulous
• White box system, a bilge water monitoring and control system for ships
• The "white box" release of the original Dungeons & Dragons rules
• White Box, Eucalyptus albens, a tree species from Australia
• Shirobako (lit. White Box), an anime television series produced by P.A.Works.

A white box (or glass box, clear box, or open box) is a subsystem whose internals can be viewed but usually not be altered.

Having access to the subsystem internals in general makes the subsystem easier to understand but also easier to hack; for example, if a programmer can examine source code, weaknesses in an algorithm are much easier to discover. That makes white box testing much more effective than black box testing but considerably more difficult from the sophistication needed on the part of the tester to understand the subsystem.

In computer hardware, a white box is a personal computer or server without a well-known brand name. For instance, the term applies to systems assembled by small system integrators and to home-built computer systems assembled by end users from parts purchased separately at retail. In this latter sense, building a white box system is part of the DIY movement. The term is also applied to high volume production of unbranded PCs that began in the mid-1980s with 8 MHz Turbo XT systems selling for just under $1000.

Because form factors like ATX and connectors such as IDE, SATA, PCI, and PCI-Express are industry-wide standards, a whole range of cases, motherboards, CPUs, hard disk drives, RAM and other parts can be obtained individually at many computer shops and assembled at home with a minimum of tools and technical skill. Alternatively, the shop itself may assemble components into a complete machine at a modest additional cost. Similarly, the less-common term "whitebook" denotes a notebook computer assembled from off-the-shelf parts.

Computer professionals and intensive computer users (especially gamers) often prefer white box computers constructed with higher quality components that they specify. as opposed to lower cost generic components often found in general purpose PCs. For these users, performance, longevity, and expansion capability take precedence over achieving the absolute lowest cost through the use of the cheapest possible components.

In 2002, around 30% of personal computers sold annually were white box systems. Although saving money is a common motivation for building one's own PC, today it is generally more expensive to build a low-end PC than to buy a pre-built equivalent.