# 😱 Awesome Falsehood [![Awesome](https://awesome.re/badge-flat.svg)](https://github.com/sindresorhus/awesome)

**A curated list of falsehoods programmers believe in.**

<p align="center">
  <a href="https://github.com/kdeldycke/awesome-falsehood/">
    <img src="./assets/awesome-falsehood-header.jpg" alt="Awesome Falsehood header image">
  </a>
</p>

<p align="center">
  <i>The logic of the world is prior to all truth and falsehood.</i><br>
  — Ludwig Wittgenstein<sup id="intro-quote-ref"><a href="#intro-quote-def">[1]</a></sup>
</p>


*Falsehood* articles are a form of commentary on a particular subject, and are
appreciated by the developer community at large for their effectiveness and
terseness. They're a convenient written form to approach an unfamiliar domain
by dispelling myths, point out common pitfalls, show inconsistencies and
subtleties.

In a sense, *Falsehood* articles are a suite of wordy unit-tests covering
extensive edge-cases provided by real-world usage.

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## Contents

- [Meta](#meta)
- [Arts](#arts)
- [Business](#business)
- [Dates and Time](#dates-and-time)
- [Education](#education)
- [Emails](#emails)
- [Geography](#geography)
- [Human Identity](#human-identity)
- [Internationalization](#internationalization)
- [Management](#management)
- [Multimedia](#multimedia)
- [Networks](#networks)
- [Phone Numbers](#phone-numbers)
- [Postal Addresses](#postal-addresses)
- [Science](#science)
- [Society](#society)
- [Software Engineering](#software-engineering)
- [Typography](#typography)

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## Meta

- [Falsehoods Programmers Believe](https://spaceninja.com/2015/12/07/falsehoods-programmers-believe/) - A
brief list of common falsehoods. A great overview and quick introduction into
the world of falsehoods.
- [Falsehoods About Programming](https://chiselapp.com/user/ttmrichter/repository/gng/doc/trunk/output/falsehoods.html) - A
humbling and fun list on programming and programmers themselves.
- [Falsehoods About Falsehoods Lists](https://github.com/kdeldycke/kevin-deldycke-blog/blob/master/content/posts/falsehoods-programmers-believe-about-falsehoods-lists.md) - Meta
commentary on how these falsehoods shouldn't be handled.


## Arts

- [Falsehoods About Music](https://literateprogrammer.blogspot.fr/2016/07/falsehoods-programmers-believe-about.html) - False
assumption that might be made in codifying music.
- [Falsehoods About Art](http://artsy.github.io/blog/2018/04/18/programmer-misconceptions-about-art/) - Common
misconceptions about art.


## Business

- [Falsehoods About Online Shopping](http://wiesmann.codiferes.net/wordpress/?p=22201) - Covers
prices, currencies and inventory.
- [Falsehoods About Prices](https://gist.github.com/rgs/6509585) - Covers
currencies, amounts and localization.
- [Falsehoods About IBANs](https://github.com/globalcitizen/php-iban/blob/master/docs/FALSEHOODS.md) - International
Bank Account Numbers are not immune to mistakes.
- [Falsehoods About Economics](http://exple.tive.org/blarg/2016/09/22/falsehoods-programmers-believe-about-economics/) - Economics
are not simple or rational.
- [Falsehoods About Cars](https://github.com/driveto/falsehoods-about-cars) - Even
something as common as defining a car is full of pitfalls.
- [CLDR currency definitions](http://unicode.org/cldr/trac/browser/tags/release-31/common/supplemental/supplementalData.xml#L81) - Currency
validity date ranges overlap due to revolts, invasions, new constitutions, and
slow planned adoption.
- [`tax`](https://github.com/commerceguys/tax) - A PHP 5.4+ tax management
library.


## Dates and Time

- [Falsehoods About Time](http://infiniteundo.com/post/25326999628/falsehoods-programmers-believe-about-time) - Seminal
article on dates and time.
- [More Falsehoods About Time](http://infiniteundo.com/post/25509354022/more-falsehoods-programmers-believe-about-time) - Part.
2 of the article above.
- [Falsehoods About Time and Time Zones](https://www.creativedeletion.com/2015/01/28/falsehoods-programmers-date-time-zones.html) - Another
takes on time-related falsehoods, with an emphasis on time zones.
- [Critique of Falsehoods About Time](https://gist.github.com/thanatos/eee17100476a336a711e) - Takes
on the first article above and provides an explanation of each falsehood, with
more context and external resources.
- [Your Calendrical Fallacy Is Thinking…](http://yourcalendricalfallacyis.com) - List
covering intercalation and cultural influence, made by a community of iOS and
macOS developers.
- [Time Zone Database](https://www.iana.org/time-zones) - Code and data that
represent the history of local time for many representative locations around
the globe.
- [The Long, Painful History of Time](http://naggum.no/lugm-time.html) - Most
of the idiosyncrasies in time keeping can find an explanation in history.
- [You Advocate a Calendar Reform](https://qntm.org/calendar) - Your idea will
not work. This article tells you why.
- [So You Want to Abolish Time Zones](https://qntm.org/abolish) - Abolishing
timezones may sound like a good idea, but there are quite a few complications
that make it not quite so.
- [The Problem with Time & Timezones](https://www.youtube.com/watch?v=-5wpm-gesOY) - A
video about why you should never, ever deal with timezones if you can help it.
- [$26,000 Overcollection by Labor Department](http://digital.vpr.net/post/rounding-error-computer-code-leads-26000-overcollection-labor-department) - The
consequence of wrong calendar accounting.
- [ISO-8601, `YYYY`, `yyyy`, and why your year may be wrong](https://ericasadun.com/2018/12/25/iso-8601-yyyy-yyyy-and-why-your-year-may-be-wrong/) - String
formatting of date is hard.
- [UTC is Enough for everyone, right?](https://zachholman.com/talk/utc-is-enough-for-everyone-right) - There
are edge cases about dates and time (specifically UTC) that you probably
haven't thought of.
- [Storing UTC is not a silver bullet](https://codeblog.jonskeet.uk/2019/03/27/storing-utc-is-not-a-silver-bullet/) - "Just
store dates in UTC" is not always the right approach.
- [Falsehoods about Unix Time](https://alexwlchan.net/2019/05/falsehoods-programmers-believe-about-unix-time/) - Mind
the leap second!
- [Why is subtracting these two times (in 1927) giving a strange result?](https://stackoverflow.com/a/6841479/57311) - Infamous
Stack Overflow answer about both complicated historical timezones, and how
historical dates can be re-interpreted by newer versions of software.
- [Critical and Significant Dates](https://web.archive.org/web/20150908004245/http://www.merlyn.demon.co.uk/critdate.htm) - From Y2K to the overflow of 32-bit seconds from unix epoch, a list of special date to watch for depending on the system.


## Education

- [Falsehoods CS Students (Still) Believe Upon Graduating](https://www.netmeister.org/blog/cs-falsehoods.html) - A
list of things (not only) computer science students tend to erroneously and at
times surprisingly believe even though they (probably) should know better.
- [Postdoc myths](https://www.cs.kent.ac.uk/people/staff/srk21/blog/2019/12/02/) - `Lots of things are said, written and believed about postdoctoral researchers that are simply not true.`.


## Emails

- [I Knew How to Validate an Email Address Until I Read the RFC](https://haacked.com/archive/2007/08/21/i-knew-how-to-validate-an-email-address-until-i.aspx/) - Provides
intricate examples that are unsuspected valid email addresses according the
RFC-822.
- [So you think you can validate email addresses (FOSDEM 2018)](https://fosdem.org/2018/schedule/event/email_address_quiz/) - Presentation
of edge-case email addresses and why you should not use regex to parse them.


## Geography

- [Falsehoods About Geography](http://wiesmann.codiferes.net/wordpress/?p=15187) - Takes
on places, their names and locations.
- [Falsehoods About Maps](http://www.atlefren.net/post/2014/09/falsehoods-programmers-believe-about-maps/) - Covers
coordinates, projection and GIS.


## Human Identity

- [Falsehoods About Names](https://www.kalzumeus.com/2010/06/17/falsehoods-programmers-believe-about-names/) - The
article that started it all.
- [Falsehoods About Names – With Examples](https://shinesolutions.com/2018/01/08/falsehoods-programmers-believe-about-names-with-examples/) - A
revisited version of the article above, this time with detailed explanations.
- Falsehoods About Gender: [#1](https://gist.github.com/garbados/f82604ea639e0e47bf44) & [#2](https://medium.com/gender-2-0/falsehoods-programmers-believe-about-gender-f9a3512b4c9c) - Gender
is part of human identity and has its own subtleties.
- [Gay Marriage: The Database Engineering Perspective](https://web.archive.org/web/20170914014648/https://qntm.org/gay) - How
to store a marriage in a database while addressing most of the falsehoods about
gender, naming and relationships.
- [Falsehoods Programmers Believe About Families](https://shkspr.mobi/blog/2017/03/falsehoods-programmers-believe-about-families/) - You
can't really define a family with strict rules.
- [Personal Names Around the World](https://www.w3.org/International/questions/qa-personal-names) - How
do people's names differ around the world, and what are the implications for
the Web?
- [XKCD #327: Exploits of a Mom](https://xkcd.com/327/) - Funny take on how
implementation of a falsehood might lead to security holes.
- [Hello, I'm Mr. Null. My Name Makes Me Invisible to Computers](https://www.wired.com/2015/11/null/) - Real-life
example on how implemented falsehood has negative impact on someone's life.
- [My name causes an issue with any booking!](https://travel.stackexchange.com/questions/149323/my-name-causes-an-issue-with-any-booking-names-end-with-mr-and-mrs) - Old
airline reservation systems considers the `MR` suffix as `Mister` and drops it.
- [HL7 v3 RIM](https://www.hl7.org/implement/standards/product_brief.cfm?product_id=186) - A
flexible data model for representing human names.
- [Apple iOS `NSPersonNameComponentsFormatter`](https://developer.apple.com/library/ios/documentation/Miscellaneous/Reference/NSPersonNameComponentsFormatter_Class/index.html) - Localized
representations of the components of a person's name.
- [Falsehoods About Me](https://skylarmacdonald.com/falsehoods/) - Issues at
the intersection of names and gender and internationalization.


## Internationalization

On character encoding, string formatting, unicode and internationalization.

- [Falsehoods About Language](http://garbled.benhamill.com/2017/04/18/falsehoods-programmers-believe-about-language) - Translating
a software from English is not as straightforward as it seems to be.
- [Internationalis(z)ing Code](https://www.youtube.com/watch?v=0j74jcxSunY) - A
video about things you need to keep in mind when internationalizing your
code.
- [Minimum to Know About Unicode and Character Sets](https://www.joelonsoftware.com/2003/10/08/the-absolute-minimum-every-software-developer-absolutely-positively-must-know-about-unicode-and-character-sets-no-excuses/) - A
good introduction to unicode, its historical context and origins, followed by
an overview of its inner working.
- [Awesome Unicode](https://github.com/Wisdom/Awesome-Unicode) - A curated list
of delightful Unicode tidbits, packages and resources.
- [Dark corners of Unicode](https://eev.ee/blog/2015/09/12/dark-corners-of-unicode/) - Unicode
is extensive, here be dragons.
- [Let's Stop Ascribing Meaning to Code Points](https://manishearth.github.io/blog/2017/01/14/stop-ascribing-meaning-to-unicode-code-points/) - Dives
deeper in Unicode and dispels myths about code points.
- [Breaking Our `Latin-1` Assumptions](https://manishearth.github.io/blog/2017/01/15/breaking-our-latin-1-assumptions/) - Most
programmers spend so much time with `Latin-1` they forgets about other's scripts
quirks.
- [Ode to a shipping label](http://i.imgur.com/4J7Il0m.jpg) - Character
encoding is hard, more so when each broken layer of data input adds its own
spice.
- [i18n Testing Data](https://github.com/patch/i18n-testing) - Compilation of
real-word international and diverse name data for unit testing and QA.
- [Big List of Naughty Strings](https://github.com/minimaxir/big-list-of-naughty-strings) - A
huge corpus of strings which have a high probability of causing issues when
used as user-input data. A must have set of practical edge-cases to test your
software against.


## Management

- [Falsehoods About Job Applicants](https://web.archive.org/web/20170114022820/https://medium.com/@creatrixtiara/falsehoods-programmers-believe-about-job-applicants-99280437c616) - Assumptions
about job applicants and their job histories aren't necessarily true.


## Multimedia

- [Falsehoods About Video](https://haasn.xyz/posts/2016-12-25-falsehoods-programmers-believe-about-%5Bvideo-stuff%5D.html) - Cover
it all: video decoding and playback, files, image scaling, color spaces and
conversion, displays and subtitles.


## Networks

- [Falsehoods About Networks](http://blog.erratasec.com/2012/06/falsehoods-programmers-believe-about.html) - Covers
TCP, DHCP, DNS, VLANs and IPv4/v6.
- [Fallacies of Distributed Computing](https://en.wikipedia.org/wiki/Fallacies_of_distributed_computing) - Assumptions
that programmers new to distributed applications invariably make.
- [There's more than one way to write an IP address](https://ma.ttias.be/theres-more-than-one-way-to-write-an-ip-address/) - Some
parts of the address are optional, mind the decimal and octal notations,
and [don't forget IPv6](https://news.ycombinator.com/item?id=20390981) either.
- [`hostname-validate`](https://github.com/jakeogh/hostname-validate) - An
attempt to validate hostnames in Python.


## Phone Numbers

- [Falsehoods About Phone Numbers](https://github.com/googlei18n/libphonenumber/blob/master/FALSEHOODS.md) - Covers
phone numbers, their representation and meaning.
- [`libphonenumber`](https://github.com/googlei18n/libphonenumber) - Google's
common Java, C++ and JavaScript library for parsing, formatting, and validating
international phone numbers. Also available for
[C#](https://github.com/twcclegg/libphonenumber-csharp),
[Objective-C](https://github.com/iziz/libPhoneNumber-iOS),
[Python](https://github.com/daviddrysdale/python-phonenumbers),
[Ruby](https://github.com/sstephenson/global_phone) and
[PHP](https://github.com/giggsey/libphonenumber-for-php).


## Postal Addresses

- [Falsehoods About Addresses](https://www.mjt.me.uk/posts/falsehoods-programmers-believe-about-addresses/) - Covers
streets, postal codes, buildings, cities and countries.
- [Falsehoods About Residence](https://twitter.com/samphippen/status/813896916534784004) - It's
not only about the address itself, but the relationship between a person and its residence.
- [Letter Delivered Despite No Name, No Address](https://twitter.com/loriskumo/status/735851511331356672) - Ultimate
falsehood about postal addresses: you do not need one.
- [The Bear with Its Own ZIP Code](https://kottke.org/19/08/the-bear-with-its-own-zip-code) - Smokey
Bear has his own ZIP Code (`20252`) because he gets so much mail.
- [Regex and Postal Addresses](https://smartystreets.com/articles/regular-expressions-for-street-addresses) - Why
regular expressions and street addresses do not mix.
- [`libaddressinput`](https://github.com/googlei18n/libaddressinput) - Google's
common C++ and Java library for parsing, formatting, and validating
international postal addresses.
- [`addressing`](https://github.com/commerceguys/addressing) - A PHP 5.4+
addressing library, powered by Google's dataset.
- [`postal-address`](https://github.com/scaleway/postal-address) - Python
module to parse, normalize and render postal addresses.
- [`address`](https://github.com/Boostport/address) - Go library to validate
and format addresses using Google's dataset.


## Science

- [Falsehoods About Systems of Measurement](https://www.stevemoser.org/posts/dev/falsehoods-programmers-believe-about-systems-of-measurement.html) - On
working with systems of measurement and converting between them.


## Society

- [Falsehoods About Political Appointments](https://twitter.com/oliver_dw/status/737930439575404544) - Designing
election systems has its own tricks.
- [Falsehoods About Women In Tech](https://gist.github.com/Su-Shee/5d1a417fa9de19c15477) - Myth
about women in STEM (Science, Technology, Engineering, Math) industries.


## Software Engineering

- [Falsehoods About Versions](https://github.com/xenoterracide/falsehoods/blob/master/versions.md) - Attributing
an identity to a software release might be harder than thought.
- [Falsehoods About Build Systems](https://pozorvlak.livejournal.com/174763.html) - Building
software is hard. Building software that builds software is harder.
- [Myths About File Paths](https://yakking.branchable.com/posts/falsehoods-programmers-believe-about-file-paths/) - Diversity
of file-systems and OSes makes file paths a little harder than we might think
of.
- [Falsehoods About REST APIs](http://slinkp.com/falsehoods-programmers-believe-about-apis.html) - Pitfalls
to be mindful of when creating and documenting APIs.
- [Falsehoods About CSVs](https://donatstudios.com/Falsehoods-Programmers-Believe-About-CSVs) - While
RFC4180 to exists, it is far from definitive and goes largely ignored.
- [Falsehoods About Package Managers](https://meta-package-manager.readthedocs.io/en/develop/falsehoods.html) - Covers
package and their managers.
- [Falsehoods About Testing](https://club.ministryoftesting.com/t/falsehoods-testers-believe/1371) - An
attempt to establish a list of falsehoods about testing.
- [Popular misconceptions about `mtime`](https://apenwarr.ca/log/20181113) - Part
of a post on why file's `mtime` comparison could be considered harmful.
- [Falsehoods About Pagination](https://www.hezmatt.org/~mpalmer/blog/2018/12/12/falsehoods-programmers-believe-about-pagination.html) - Why
your pagination algorithm is giving someone (possibly you) a headache.
- [Rules for Autocomplete](http://jeremymikkola.com/posts/2019_03_19_rules_for_autocomplete.html) - Not
falsehoods *per-se*, but still a great list of good practices to implement
autocompletion.
- [`9999999999999999.0` - `9999999999999998.0`](http://geocar.sdf1.org/numbers.html) - A
kind of falsehood on numbers, and floats vs decimals.
- [Falsehoods About Search](https://opensourceconnections.com/blog/2019/05/29/falsehoods-programmers-believe-about-search/) - Why
search (including analysis, tokenization, highlighting) is deceptively complex.
- [Hi! My name is…](https://www.youtube.com/watch?v=NIebelIpdYk) - This talk
could have been named "falsehoods about usernames (and other identifiers)".
- [Myths about `/dev/urandom`](https://www.2uo.de/myths-about-urandom) - There
are a few things about `/dev/urandom` and `/dev/random` that are repeated again and
again. Still they are false.
- [Myths about CPU Caches](https://software.rajivprab.com/2018/04/29/myths-programmers-believe-about-cpu-caches/) - Misconceptions
about caches often lead to false assertions, especially when it comes to
concurrency and race conditions.
- [The Hidden Complexity of Downloading Favicons, Told in 15+ Edge Cases](https://www.simplecto.com/complexity-downloading-favicons-told-in-15-plus-edge-cases/) - Downloading that little icon you see in you browser tabs should be a simple exercise. It turned out to be a lot more complicated than you think. Be vigilant that you are not shaving a Yak.
- [Norway is not False](https://mobile.twitter.com/chrisjrn/status/1232016100038266880) - Norway's ISO country code is also valid YAML for False.


## Typography

- [Falsehoods About Fonts](https://github.com/RoelN/Font-Falsehoods) - Assumptions
about typography on the web and in desktop applications.
- [Truths programmers should know about case](https://www.b-list.org/weblog/2018/nov/26/case/) - A
complete reverse of the falsehoods format, on the topic of case (as in uppercase
and lowercase text).


## Contributing

Your contributions are always welcome! Please take a look at the
[contribution guidelines](./.github/contributing.md) first.


## License

[![CC0](https://mirrors.creativecommons.org/presskit/buttons/80x15/svg/cc-zero.svg)](https://creativecommons.org/publicdomain/zero/1.0/)
Content of this repository is licensed under the [Creative Commons CC0 license](https://creativecommons.org/publicdomain/zero/1.0/).
To the extent possible under law, [Kevin Deldycke](https://kevin.deldycke.com)
has waived all copyright and related or neighboring rights to this work.

The [header image](./assets/awesome-falsehood-header.jpg) is based on a modified
[photo taken in February 2010 by Iza Bella](https://commons.wikimedia.org/wiki/File:BLW_Truth_and_Falsehood.jpg),
distributed under a [Creative Commons BY-SA 2.0 UK
license](https://creativecommons.org/licenses/by-sa/2.0/uk/deed.en).

<a name="intro-quote-def">[1]</a>: [*Notebooks, 1914-1916*, page 14e](https://archive.org/details/notebooks191419100witt/page/n35) (Harper & Brothers, New York, 1961). [\[↑\]](#intro-quote-ref)
