{{short description|System whose internals can be viewed but not altered}} {{Hatnote|"Open box" redirects here. "Open box" is also the name of the visible symbol ␣ that is sometimes used to indicate a space. See [[whitespace character]].}} {{Distinguish|White-box testing|White-box cryptography|White box (computer hardware)}} {{Black-box}}
A '''white box''' (or '''glass box''', '''clear box''', or '''open box''') is a [[subsystem]] whose internals can be viewed but usually not altered.<ref>Patrick J. Driscoll, "Systems Thinking," in Gregory S. Parnell, Patrick J. Driscoll, and Dale L. Henderson (eds.), ''Decision Making in Systems Engineering and Management'', 2nd. ed., Hoboken, NJ: Wiley, 2011, 40.</ref> The term is used in [[systems engineering]], [[software engineering]], and in [[intelligent user interface]] design,<ref>{{cite book |last1=Höök |first1=Kristina |last2=Karlgren |first2=Jussi |last3=Waern |first3=Annika |last4=Dahlbäck |first4=Nils |last5=Jansson |first5=Carl Gustaf |last6=Karlgren |first6=Klas |last7=Lemaire |first7=Benoît |title=Adaptive Hypertext and Hypermedia |chapter=A Glass Box Approach to Adaptive Hypermedia |date=1998 |page=143-170|doi=10.1007/978-94-017-0617-9_6 |isbn=978-90-481-4944-5 }}</ref><ref>{{cite journal |last1=Karlgren |first1=Jussi |last2=Höök |first2=Kristina |last3=Lantz |first3=Ann |last4=Palme |first4=Jacob |last5=Pärgman |first5=Daniel |title=The glass box user model for filtering |journal=Fourth International Conference on User Modeling |date=1994}}</ref> where it is closely related to recent{{When|reason=too vague|date=October 2025}} interest in [[explainable artificial intelligence]].<ref>{{cite journal |last1=Raj |first1=Arun |title=Explainable AI: From black box to glass box |journal=Journal of the Academy of Marketing Science |date=2020 |volume=48 |issue=1 |page=137-141|doi=10.1007/s11747-019-00710-5 }}</ref><ref>{{cite journal |last1=Höök |first1=Kristina |last2=Karlgren |first2=Jussi |last3=Waern |first3=Annika |title=A glass box intelligent help interface |journal=First Workshop on Intelligent Multimodal Interfaces |date=1995}}</ref>
Having access to the subsystem internals in general makes the subsystem easier to understand, but also easier to [[hack (technology slang)|hack]]; for example, if a programmer can examine source code, weaknesses in an algorithm are much easier to discover.{{Fact|date=July 2015}} 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.
The notion of a "Black Box in a Glass Box" was originally used as a metaphor for teaching complex topics to computing novices.<ref>{{cite journal |last1=du Boulay |first1=Benedict |last2=O'Shea |first2=Tim |last3=Monk |first3=John |title=The black box inside the glass box: presenting computing concepts to novices |journal=International Journal of Man-Machine Studies |date=1981 |volume=14 |issue=3 |page=237-249|doi=10.1016/S0020-7373(81)80056-9 }}</ref>
[[File:Mathematical models for complex systems.jpg|thumb|Mathematical models for complex systems]]
==See also== * [[Black box]] * [[Gray-box testing]]
==References== {{Reflist}}
[[Category:Software testing]]
{{soft-eng-stub}}