Emoji

Emoji, also known as Emoticon, was a system of communication with the use of smileys and other pictograms or images. According to the Twelfth Doctor, no other species in the universe aside from humans used emojis. (TV: Smile) The Ninth Doctor included emoticons as a popular pastime of humans in the 21st century. (AUDIO: The Other Side)

It was popular on Earth during the 21st century, and remained a popular form of language centuries later, a colony planet. It was used by the Emojibots as their primary form of expression. The colonists also wore mood indicators that expressed their emotions in order to better communicate with the robots. (TV: Smile)

The Eighth Doctor felt that intonation, as in speech, was conveyed in a text message with "those little faces" and via "amusing punctuation". (AUDIO: Dead Time)

Jay sent Norton Folgate vegetable emojis while the latter was in Tyler Steele's body, to Norton's confusion. The two soon arranged to meet for sex. (AUDIO: Another Man's Shoes)

In a new timeline created by Josiah W. Dogbolter, in which Ace, along with the Seventh Doctor and Narvin, was integrated into the Solar System, her boyfriend, Alex, received threatening emojis from his employers when he was late to his work as a newsreader in the 82nd century. (AUDIO: The Quantum Possibility Engine)

There came a point when it was unnecessary to make a mobile phone's memory any bigger, as there were only so many human emotions in need of emoticons to express them. (PROSE: The Eyeless)

Known emoji
Known emoji included the following pictograms:
 * 😃 – smiling face with open mouth, indicating being very happy (TV: Smile)
 * 🙂 – slightly smiling face, indicating happiness (TV: Smile)
 * 😒 – unamused face, indicating slight dissatisfaction (TV: Smile)
 * 😠 – angry face (TV: Smile)
 * 😕 – puzzled face (TV: Smile)
 * ☹️ – frowning face (TV: Smile)
 * 😮 – face with open mouth (TV: Smile)
 * 😦 – frowning face with open mouth (TV: Smile)
 * 😧 – anguished face (TV: Smile)
 * 😢 – crying face (TV: Smile)
 * 😓 – face with cold sweat, indicating stress (TV: Smile)
 * 😭 – crying face with tears streaming down both cheeks, indicating being extremely unhappy (TV: Smile)
 * 🤨 – face with raised eyebrow, indicating being intrigued (TV: Smile)
 * 😴 – sleeping face (TV: Smile)
 * 💀 – a skull, used as a symbol for death (TV: Smile)
 * 👍 – thumbs up, indicating approval (TV: Smile)
 * 💡 – a light bulb, used as a symbol for new ideas (TV: Smile)
 * 💷 – pound sterling, indicating profit (TV: Smile)
 * 🔫 – gun (TV: Smile)
 * 🗝️ – key, indicating opening something (TV: Smile)
 * ❗️ – exclamation mark (TV: Smile)
 * ❓ – question mark, indicating confusion or a question being asked (TV: Smile)
 * 🤐Face with cross in place of its mouth (TV: Smile)

Behind the scenes

 * The 2016 Doctor Who Adventure Calendar introduced the Doctor Who emoji quiz, in which the goal is to guess which story is being told through emoji. This "festive edition" of the game included 3 stories to decipher.
 * While most of the emoji used in Smile are part of the Unicode emoji set in the real world, at least one is not present in the real set; there is no emoji for a face with cross in place of its mouth. However, new emoji are still being regularly added to Unicode. One of the pictograms used in the episode, the raised eyebrow emoji, was added only after the episode had been filmed.