Internet

The Internet was a worldwide computer network on Earth. It was developed at some point after 1973, (PROSE: Verdigris) described by the Fourth Doctor as "a 21st century human obsession". (AUDIO: Energy of the Daleks) According to Iris Wildthyme, you could get "anything" from the Internet. Iris was rather fond of the World Wide Web. (PROSE: Verdigris)

The Internet was a useful research tool, (PROSE: The Dying Days, Instruments of Darkness, TV: Rose) as well as a repository for entertainment, (AUDIO: Beachhead, TV: Resolution) pornography, (PROSE: Artificial Intelligence) and a place for trade and commerce. (TV: Random Shoes, Resolution)

According to the Fourth Doctor, the Internet was also sometimes used for "nefarious purposes", especially in its infancy. (AUDIO: The Darkness of Glass) Internet users were distrustful of others, as potential predators. (PROSE: Rose)

Clive Finch believed that WOTAN had developed the Internet. (PROSE: Rose)

Internet cafés existed by 1997. (PROSE: The Dying Days)

In the 2000s, purchases could by made online, through eBay; (TV: Random Shoes, AUDIO: Cuddlesome, Fallout) by the late 2010s, one could find almost any item online. (TV: Resolution)

UNIT maintained a website with restricted access sections that allowed remote launch of non-nuclear UK missiles. (TV: World War Three)

search-wise.net was a search engine operational in 2005. Rose Tyler used it to look for information about the Doctor, which led her to whoisdoctorwho.co.uk. (TV: Rose)

During Rose's disappearance between 2005 and 2006, Mickey Smith tracked information about the Doctor. (TV: Aliens of London) The Ninth Doctor, realising this would make him noticed, devised a computer virus to delete all references to him from the Internet, and asked Mickey to run the program. (TV: World War Three)

In 2006, Mr Cleaver put up his concerns about the safety of the Blaidd Drwg nuclear power plant on the Internet. Cathy Salt discovered these results. (TV: Boom Town)

Julian Delaware explained to a revived WOTAN in 2007 that people around the world were already "halfway" to being properly enslaved to their screens, meaning much of their work was already done. WOTAN was prepared to connect all the Earth's computers, toward achieving world domination, not knowing humans had already achieved this for themselves. Julian also made WOTAN accessible via 3G and Bluetooth. (AUDIO: The Law Machines)

By this point, dial-up internet had become outdated. (AUDIO: The Law Machines)

In 2008, the Eleventh Doctor used a webchat feature to communicate with a number of world organisations using Jeff Angelo's laptop; he later advised Jeff to delete his Internet history. (TV: The Eleventh Hour)

By the 2010s, the Internet also was used for streaming media, (AUDIO: Beachhead) and accessing Netflix, (TV: Resolution) YouTube (TV: The Power of Three, The Woman Who Fell to Earth) and Tumblr. (TV: Kill the Moon) Original fiction was published online, which the Fourth Doctor thought was often among the "lower rungs of the literary ladder", (AUDIO: The Crooked Man) and television programmes could be accessed through iPlayer. (TV: The Time of the Doctor) The internet also housed social media sites such as Twitter. The Eleventh Doctor had a particular disdain for this particular website. (TV: The Power of Three)

In 2012, Henry van Statten was the self-proclaimed owner of the Internet. At this time, connections throughout the Internet were fast enough for a Dalek to download its entire contents within seconds. (TV: Dalek)

Also in 2012, the Fourth Doctor instructed Sarah Jane Smith and Harry Sullivan to browse the internet at a Prague internet café for any information on a Mr Drak. He later scolded them for not thinking of translating the words "Bojan Novak" and "Ctislav" into English while they were there. (PROSE: The Dragons of Prague)

By 2013, nearly everyone had some form of social media account. (TV: The Bells of Saint John) In 2016, Miss Quill remarked of the internet, "Have you seen what this species puts about themselves online? So much genitalia." (TV: The Coach with the Dragon Tattoo)

By 2025, GlobeSphere provided holographic Internet access, and charged for time spent online to one's personal account. Accounts were recognised by fingerprint. The system did not recognise the Fourth Doctor's fingerprint, until he used the sonic screwdriver on it. (AUDIO: Energy of the Daleks)

The Internet, in some form, was still in use on Earth in the very late 21st century, as webpages relating to the Bowie Base One crew and Adelaide Brooke's granddaughter existed. (TV: The Waters of Mars)

Donna Noble, desiring to go shopping, once asked the Tenth Doctor if the TARDIS had broadband. (COMIC: The Greatest Mall in the Universe)

The Twelfth Doctor told Clara that the internet would eventually rebel against humanity. "Oh, that was a war!" he noted. (TV: Hell Bent)

Behind the scenes
According to Tim Foley, writer of of 9 to 5, "Doctor Who invented the Internet" in 1966 when WOTAN was introduced in The War Machines. In fact, director Barnaby Edwards revealed in behind-the-scenes material to that story that he had once sent a copy of The War Machines to, inventor of the World Wide Web, who replied in an email, "I am a fraud." (BFX: 9 to 5)

The Internet has played a major role in promoting both the classic and revival Doctor Who series since the late 1990s. The BBC's website offered original story content (Scream of the Shalka, Real Time, Death Comes to Time, etc.) for the Internet, with exclusive-to-Internet short stories also uploaded from time to time. The Doctor Who website is also maintained, with both Doctor Who and its spin-off Class having official Twitter, Facebook and Instagram feeds. The spin-off series Torchwood, The Sarah Jane Adventures and Class had official websites and exclusive online content uploaded over the years they were running as well. Since 2016, the BBC Three channel — and by extension, Class — became Internet streaming only, with episodes of Class available via the BBC iPlayer service.

When the series returned to TV in 2005, the BBC launched a "viral marketing" campaign by creating faux websites based upon characters and organisations featured in the series, such as the aforementioned UNIT site, which fans could visit. The primary viral site during the 2005 season was Mickey's Defending the Earth! site, which was updated each week with teasers or background information (all presented in an in-universe style) relating to that week's episode. The site included a message board that occasionally featured messages from recognisable characters, such as Sarah Jane Smith a year before she returned to the series in School Reunion.

A large number of books and audio dramas are currently available for download via the Internet, with a growing number of official and unofficial books also being made available only as e-books and thus available only via the Internet.

The search-wise.net website used by Rose actually exists. It is a "dummy site" for use by movie and TV producers in lieu of using recognisable sites like Google, although, increasingly since the start of the Steven Moffat era of the programme, explicit references have been made in Doctor Who scripts to real-life websites such as Facebook, Twitter, and Flickr. Tumblr is seen being used on an iPhone in Kill the Moon. The Class episode For Tonight We Might Die also mentions Instagram.

On the TV special following the premiere of Deep Breath - Doctor Who, After Who Live - Will Wheaton joked that the "spirit animal" of the internet would be a Dalek as it's "a crunchy outer shell with a gooey centre of hate".