[[quoteright:296:http://static.tvtropes.org/pmwiki/pub/images/0.jpg]]
[[caption-width-right:296:Alice and Bob [[note]]cartoon by John Richardson in ''Physics World'', March 1998]][[/note]]

When the interaction between two hypothetical characters is needed to explain or describe some system, they are nearly always called [[AliceAllusion Alice]] and Bob. Alice and Bob -- A and B. This duo originally started out as a standardized way to explain cryptography. Over time, the duo has been adopted in explanations of mathematics, physics, quantum effects, and other arcane places, but have also been seen in fiction. They are also found in a surprising number of trope definitions.

Where more than two characters are needed, other names are used, such as Carol and Charlie. Some names have acquired standard meanings, such as Eve the Eavesdropper. Lists of these can be found in Bruce Schneier's book Applied Cryptography, and at [[http://en.wikipedia.org/wiki/Alice_and_Bob that other wiki]].

The use of "Alice and Bob" when describing a trope situation is a nice way to speak of generic persons while avoiding clunky pronoun constructions like "his or her" or "s/he." It is suggested in General Suggestions for this very reason. Of course, some Tropers (especially those who are actually ''named'' Alice and/or Bob) yearn for a little more originality. That's where AerithAndBob come in. [[AvertedTrope Or Jim]] [[VideoGame/{{Bioshock}} and Mary]]. Or Literature/DickAndJane.

See also ThoseTwoGuys, GreekChorus.
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!!Examples:

[[foldercontrol]]

[[folder: Film ]]

* Movie and TV example: ''Bob & Carol & Ted & Alice''.
* HowToLoseAGuyInTenDays has a romantic couple of Andy Anderson and Benjamin Berry.

[[/folder]]

[[folder: Literature ]]

* In most cryptography textbooks, communications are presented as being between Alice and Bob, and must be secured from a third-party interloper named Eve (for Eavesdropper, of course!). If the problem requires the involvement of more than two parties, then Charlie and Donna may be introduced. This is the basis for the Webcomic/{{XKCD}} reference. Other character names sometimes used for special purposes include Mallory (a ''mal''icious active adversary, capable of changing the messages sent between Alice and Bob, whereas Eve merely listens), Trent (a mutually ''tr''usted third party, whom Alice and Bob might prevail upon to execute protocols in which they don't trust each other), and Peggy and Victor (the prover and verifier, respectively, in zero-knowledge proofs).
** Game Theory books often use an adaptation of Alice and Bob in "Rose and Colin" (rows and columns on game theory charts), with "Larry", or "layer" thrown in for three person games.
*** Game Semantics books tend to use Abelard and Eloise (for resemblance to the universal and existental quantifier symbols, which are an inverted A and a backwards E). They are also the names of a medieval logician and his lover.
* Alice and Bob are the names of the parents in Vernor Vinge's ''Rainbows End'', and a government official is named Eve Mallory.
* E. R. Emmet's "Our Factory" puzzles feature "Alf", "Bert", "Charlie", and so on.
* In [[http://www.guidetojapanese.org/learn/ Tae Kim's Guide to Learning Japanese]], a free, online textbook, Alice and Bob are the main characters used in example dialogues and mock conversations, posing as foreign exchange students in Japan.

[[/folder]]

[[folder: Live Action TV ]]

* TV and Movie example: ''Bob & Carol & Ted & Alice''.
* One of the [[VanityPlate logos]] at the end of ''The Bonnie Hunt Show'' (2008-2010) is for "Bob & Alice Productions".
** Bonnie's Hunt's parents are named Bob and Alice so it is either just a reference to her parents or both.

[[/folder]]

[[folder: Music Tropes ]]

* Nerdcore Rap artist MC Plus+ has a song about cryptography named "Alice and Bob".

[[/folder]]

[[folder: Newspaper Comics ]]

* ''ComicStrip/{{Dilbert}}'' does this in a one-way fashion with "Ted TheGenericGuy," who has no consistent personality and shows up whenever a generic extra is needed. [[ButtMonkey Bad things tend to happen to him.]]
** His official bio notes that there may actually be multiple Teds, but nobody's sure.

[[/folder]]

[[folder: Oral Tradition ]]

* [[http://www.conceptlabs.co.uk/alicebob.html The Story of Alice and Bob]] is a humorous after-dinner speech recounting their mythology.
* A collection of [[http://web.archive.org/web/20060619074924/http://rogers.phy.bris.ac.uk/denzil/denweb4.html Alice and Bob jokes]].

[[/folder]]

[[folder: Video Games ]]

* Used in a very surreal CyberSpace level in ''VideoGame/WorldOfGoo'' called "Alice and Bob and the Third Party," where you intercept information-goo transmitted from [-[=cosmicGrrrl!=]-] to [-[=LaconicCrusadr13=]-].
* Used as examples for an explanation of [[spoiler: quantum teleportation]] in ''{{Remember11}}''.

[[/folder]]

[[folder: Web Comics ]]

* Parodied in ''Webcomic/{{xkcd}}'':
** [[http://xkcd.com/177/ 177]]: Eve tells her side of the story.
** [[http://xkcd.com/1323/ 1323]]: Computer scientists will listen to any boring story if the participants are Alice and Bob & co.
* [[http://tropeoverdosed.byethost6.com/?p=6 The main characters]] of ''TropeOverdosedTheWebcomic''
* Alice is introduced in the opening chapter of ''FreakAngels''. In the epilogue, [[spoiler:she's explaining the story to a military officer named Bob.]]
* In Webcomic/RageComics, Derp and Derpina are the equivalent.

[[/folder]]

[[folder: Web Original ]]

* There's actually a blog '''named''' ''Blog/{{Alice and Bob}}''
* [[http://catalogliving.net/ Catalog Living]] has the imaginary Elaine and Gary.
* They (or rather, [[LegacyCharacter a number of male-female duos named after them]]) are the main protagonists of ''JustForFun/TheTroperiaSaga''.

[[/folder]]

[[folder: Real Life ]]

* Alice and Bob really are quantum- a professor at the University of Washington has used two separate remote cameras, named Alice and Bob, to test the theory of non-locality and its potential for time travel, by attempting to receive a message before it's sent. The experiment hasn't yielded results so far, but it's telling.
* In {{UsefulNotes/linguistics}}, it's more often John and Mary.

[[/folder]]

[[folder: Tv Tropes Wiki ]]

[[index]]
* AccidentalMisnaming
* AcidRefluxNightmare
* AdaptationalAttractiveness
* AmnesiacLiar
* BathroomStallOfOverheardInsults
* BelatedHappyEnding
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[[/index]]
* Numerous PlayingWith pages.
* ? and more.
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