FAQs (Frequently Asked Questions)
This FAQ answers some questions related to the technical workings of Wikipedia, including software and hardware. Check out
Wikipedia:FAQ/Main Page for additional main page-specific technical information.
Note: If you're trying to get help for a specific technical problem that isn't answered by the FAQs, read
Wikipedia:Troubleshooting or ask question at the
technical village pump.
What happens if two or more people are editing the same page?
- When the second person (and later people) attempts to save the page, MediaWiki will attempt to merge their changes into the current version of the text. If the merge fails then the user will receive an "edit conflict" message, and in some cases the opportunity to merge their changes manually. If multiple consecutive conflicts are noticed, it will generate a slightly different message. This is similar to
Concurrent Versions System (CVS), a widely used software version management system.
Help:Edit conflict for more information.
How do I recover a password I have forgotten?
- If you entered your e-mail address when you signed up, you can have a new password generated. Click on the "
Log in" link in the upper-right corner. Follow the link near the bottom of the page titled "Forgot your password?"
- On the
Reset password page, which loads, enter either your username or your email address (the one you associated with the username), and select the Reset password button.
- You should receive an e-mail message with a new random password; you can use it to log in. You will then be presented with the opportunity to change your password to something you'll remember.
Help:Logging in#What if I forget my password? if this does not work.
How do I change my password?
- You can change your password via
Special:ChangePassword; you can also find a link to this in
How do I report a bug?
- The developers use the
Phabricator bug tracking tool to keep track of bugs. Anybody is welcome to create an account there and report any bugs they encounter; however, if you prefer, you can post about your bug at the
technical village pump. For more information, see
How do I suggest a new feature?
- To make an official feature request, use
Phabricator. For information on using Phabricator, please see
What software is used to run Wikipedia?
- Wikipedia originally ran
UseModWiki, a general wiki script by
Clifford Adams written in
Perl. In January 2002, we switched to the
Phase II software written by
Magnus Manske in
PHP, which in turn was completely overhauled the following July primarily by
Lee Daniel Crocker to create what we now call
MediaWiki. Currently, most of the PHP code in Mediawiki at Wikimedia Foundation uses
Special:Version for software versions. The Wikipedia servers'
operating system is
Linux, primarily using the
Debian distribution. Some older servers run
Ubuntu. For details see
How about the hardware?
History of Wikipedia hardware
- A brief history of Wikipedia serving:
- Phase I: January 2001 – January 2002
- One of Bomis' servers hosted all Wikipedia wikis running on
- Phase II: January 2002 – July 2002
- One of
Bomis' servers hosted all Wikipedia wikis; English and meta running on the php/mysql-based new software, all other languages on UseModWiki. Runs both the database and the web server on one machine.
- Phase IIIa: July 2002 – May 2003
- Wikipedia gets own server, running English Wikipedia and after a bit meta, with rewritten PHP software. Runs both the database and the web server on one machine.
- One of Bomis' servers continues to host some of the other languages on UseModWiki, but most of the active ones are gradually moved over to the other server during this period.
- Phase IIIb: May 2003 – Feb 2004
- Wikipedia's server is given the code name "pliny". It serves the database for all phase 3 wikis and the web for all but English.
- New server, code name "larousse", serves the web pages for the English Wikipedia only. Plans to move all languages' web serving to this machine are put on hold until load is brought down with more efficient software or larousse is upgraded to be faster.
- One of Bomis' servers continued to host some of the other languages on UseModWiki until it died. All are now hosted on pliny; a few more of the active ones have been gradually moved over to the new software, and an eventual complete conversion is planned.
- Phase IIIc: Feb 2004 to Present
- Wikipedia gets a whole new set of servers, paid for through donations to the non-profit
- The new architecture has a new database server (suda), with a set of separate systems running Apache, as well as "squids" that cache results (to reduce the load). More details are at
New servers bought as needed, bringing total number to about 350 servers.
How about the connection?
- Wikimedia Foundation has multiple facilities spread out worldwide served by different bandwidth suppliers.
- See the
Wikipedia:Statistics page for information about bandwidth usage.
How big is the database?
- As of 2012, the combined size of the databases being backed up was between 4 and 6 TB for the copies of the Primary database, and perhaps 27 TB for the images and media (based on
- Early in Wikipedia's history, in February 2003 the database was about 4 GB in size. By April 2004, it was growing at about 1 to 1.4 GB per week, and by October 2004, it had grown to about 170 GB.
- Uploaded files took up approximately 372 gigabytes lc, excluding thumbnails.
- For current information, see
- Compressed database dumps can be downloaded at
What kind of
markup language does Wikipedia use?
- Wikipedia uses a very simple markup based on
UseModWiki. For more details, see
Wikipedia:How to edit a page.
Why not use
- The short answer is: for simplicity and security.
- And now the longer answer. Wikipedia, and
wikis in general, are meant to be edited on the fly. HTML is not easy to use when you simply want to write an article. Creating links gives us a particularly dramatic example. To link to the Paris article using HTML, one would have to type
- <a href="https://webot.org/info/en/?search=Paris">Paris</a>
- Using MediaWiki markup is much easier:
- A special markup language even allows you to "transclude" special snippets of code, called
templates, into wiki pages. (You can also "substitute" the code for that template, effectively copying and pasting it into the document, but this is a waste of space and is obnoxious to other users who try to edit but find that they have to scroll through large amounts of template code. Substitution is, however, preferred in some cases.)
- Then there's security. Different
web browsers have bugs that can be exploited via HTML. Malicious users could also do things like
So we can't use any HTML?
- That's not true. Certain
HTML tags work—namely the ones in
this list. It's still best not to rely on using HTML directly, because support for these tags is not always guaranteed to remain; they might affect the results achieved with
VisualEditor; and if you can achieve your needed effect using only WikiText markup, you're most likely to get a result that is stable when the MediaWiki software is updated.
- Also see
Wikipedia:How to edit a page.
What about non-
ASCII characters, and special symbols?
- Wikipedia uses Unicode (specifically the UTF-8 encoding of Unicode) and most browsers can handle it but font issues mean that more obscure characters may not work for many users.
Meta:Help:Special characters page for a detailed discussion of what is generally safe and what isn't. This page will be updated over time as more browsers come to support more features.
http://www.unicode.org/help/display_problems.html for instructions on how to enable Unicode support for most platforms.
What about math topics, which require many special symbols, fonts, and graphics?
- Just use
Is it possible to download the contents of Wikipedia?
- Yes, the complete text and editing history of all Wikipedia pages can be downloaded. See
- Note that downloading the database dumps is much preferred over trying to spider the entire site. Spidering the site will take you much longer, and puts a lot of load on the server (especially if you ignore our
robots.txt and spider over billions of combinations of diffs and whatnot). Heavy spidering can lead to your spider, or your IP, being barred with prejudice from access to the site. Legitimate spiders (for instance search engine indexers) are encouraged to wait about a minute between requests, follow the robots.txt, and if possible only work during less loaded hours (2:00-14:00 UTC is the lighter half of the day).
- The uploaded images and other media files are not currently bundled in an easily downloadable form; if you need one, please contact the developers on the
wikitech-l mailing list. Please do not spider the whole site to get images.
Is there a library to query Wikipedia in my programming language?
- Yes, client code is available in many languages, see
here for a non-exhaustive list. See also the
API documentation and our
- Cookies are not required to read or edit Wikipedia, but they are required in order to
log in and link your edits to a user account.
- When you log in, the wiki will set a temporary session cookie which identifies your login session; this will be expired when your browser exits (or after an inactivity timeout), and is not saved on your hard drive.
- Another cookie will be saved which lists the user name you last logged in under, to make subsequent logins just a teensy bit easier. (Actually two: one with your name, and one with your account's internal ID number; they must match up.) These cookies expire after 365 days. If this worries you, clear your cookies after completing your session.
- If you check the "remember my password" box on the login form, another cookie will be saved with a token that authenticates you to our servers (which is unrelated to your password). As long as this remains valid, you can bypass the login step on subsequent visits to the wiki. The cookie
expires after 365 days, or is removed if you
log out. If this worries you, don't use the option. (You should not use it on a public terminal!)
- See the
cookie statement linked at the bottom of each page for other details.
Hey! Why was I automatically logged out?
- This could be a result of your cookie, browser cache, or firewall/Internet security settings. Or, to quote
Tim Starling (referring to a question about "remembering password across sessions"):
- "The kind of session isn't a network session strictly speaking, it's an HTTP session, managed by PHP's
session handling functions. This kind of session works by setting a cookie, just like the "remember password" feature. The difference is that the session cookie has the "discard" attribute set, which means that it is discarded when you close your browser. This is done to prevent others from using your account after you have left the computer.
- The other difference is that PHP sessions store the user ID and other such information on the server side. Only a "session key" is sent to the user. The remember password feature stores all required authentication information in the cookie itself. On our servers, the session information is stored in
memcached, a system for non-durable (unreliable) caching. Session information may occasionally be lost or go missing temporarily, causing users to be logged out. The simplest workaround for this is to use the remember password feature, as long as you are not worried about other people using the same computer." from the
Wikipedia:Village pump (technical) on May 4, 2005 (italics added).
- In other words: click the "remember me" box when logging in.
- See also
The software that runs Wikipedia is great! Can I use it for my site?
- You can, but depending on your needs you might be better served using something else;
MediaWiki is big and complex. See first
Wiki software for a list of alternative wiki software.
- If, after scanning, you're still sure you want to use MediaWiki, see
the MediaWiki web site for details on downloading, installing and configuring the software.
Can I add a page hit counter to a Wikipedia page?
- To view page hits, go to that page. Then go to its history page, View history. Then choose Page view statistics to access the
Pageview stats tool.
- Technical details about the underlying pageview definition, and other sources of raw pageview data (including dumps and
an API) can be found
Low-bandwidth wireless Wikipedia
- Users of mobile devices (smartphones, etc.) should consider browsing the mobile version of Wikipedia, by clicking the "Mobile view" link at the bottom of any page, or visiting the URL
en.m.wikipedia.org. It is suited to touch devices and will save bandwidth.
- Alternatively, to view a low-bandwidth
Main Page suitable for wireless users, select the
Wikipedia:Main Page alternative (simple layout) link. That main page has a link to the
text-only version of the main page. For now, direct entry of the URL into your wireless device's browser is the most convenient way to get to the articles. If you know a one-word article, such as
Science, you can use that article to gain entry to your favorite topics.
Is the "random article" feature really random?
- No, although it's random enough to provide a small sample of articles reliably.
- In the Wikipedia
database, each page is assigned a "random index", which is a random floating point number uniformly distributed between 0 (inclusive) and 1 (exclusive). The "random article" feature (Special:Random) chooses a random
double-precision floating-point number, and returns the next article whose random index is greater than the selected random number. Some articles will have a larger gap before them, in the random index space, and so will be more likely to be selected. So the actual probability of any given article being selected is in fact itself random.
- The random index value for new articles, and the random value used by Special:Random, is selected by reading two 31-bit words from a
Mersenne twister, which is seeded at each request by PHP's initialisation code using a high-resolution timer and the PID. The words are combined using:
- (mt_rand() * $max + mt_rand()) / $max / $max
- Some old articles had their page_random value reset using MySQL's RAND():
- rand_st->seed1=(rand_st->seed1*3+rand_st->seed2) % rand_st->max_value;
- rand_st->seed2=(rand_st->seed1+rand_st->seed2+33) % rand_st->max_value;
- return (((double) rand_st->seed1)/rand_st->max_value_dbl);
- Due to
a bug, many pages created in 2004 and 2005 used to have non-random page_random values; this was corrected in 2018.
Are page hit counters available?
- There is an advanced
pageviews analysis tool, maintained by the Wikimedia Foundation, which allows you to view hit counts for one page or for multiple pages concurrently. "Page information" under "Tools" in the desktop sidebar shows "Page views in the past 30 days" with a link to a simple graph. Additionally, the weekly
Top 25 Report provides a list of the 25 most popular articles in the last week.
- For more details please see
Wikipedia:Technical FAQ#Can I add a page hit counter to a Wikipedia page?
Can I access Wikipedia via HTTP, due to problems using HTTPS?
- No. In 2015, the
Wikimedia Foundation decided to move to only allow access via
HTTP access is no longer available, and automatically redirects requests to
HTTP Strict Transport Security is enabled, so recent browsers should actually refuse to even attempt to connect via HTTP (automatically rewriting URLs into HTTPS before connecting), after the first successful connection via HTTPS.
Are there currently problems with the servers or network?
- For the current server or network status, please see
Wikimedia Foundation Grafana.
I have a problem not on this list, where do I go?
Troubleshooting—if it's not on there try the
village pump. For help with a particular software task see
Wikipedia:Computer help desk.
More FAQ topics
FAQs (Frequently Asked Questions)