Paper was a material made from wood or a similar materials. Paper was often used as something to write on. (TV: Human Nature, Silence in the Library / Forest of the Dead)
Psychic paper was a blank, white card that had special properties. When shown to a person, it could usually induce them to see whatever the user wished them to see printed on it. This was commonly used by the Doctor, particularly in his ninth, (TV: The End of the World, The Long Game, The Empty Child) tenth, (TV: New Earth, Army of Ghosts, The Shakespeare Code, The Unicorn and the Wasp) eleventh (TV: The Lodger, A Christmas Carol) and twelfth incarnations. (TV: Mummy on the Orient Express, Dark Water) Companions of the Doctor such as Rose Tyler, (TV: Army of Ghosts) Martha Jones (TV: Evolution of the Daleks) and Clara Oswald (TV: Flatline) also made use of the paper, while Jack Harkness had psychic paper of his own. (TV: The Empty Child) Suggestibility paper was a material similar to psychic paper. (COMIC: Fugitive)
A speech by British Prime Minister Neville Chamberlain in 1938, following a conference in Munich intended to deal with the crisis in Europe caused by Nazi Germany expansionism, opened with the words: "I have in my hand a piece of paper..." (PROSE: Illegal Alien) Said paper promised that there would be "peace in our time." (PROSE: One Wednesday Afternoon) However, it was not to be. (PROSE: Timewyrm: Exodus, Just War, AUDIO: Neverland, Just War)
After they left him at Winterborne School for Christmas and Whitsun, Luke Pendrell remarked that his mother and father would likely give him another cheque and a hasty apology written on Claridge's note-paper. (HOMEVID: The Devil of Winterborne)
The Tenth Doctor met a group of Cybermen while holding a sheet of A4 paper on a stick in the place of a plain white flag, which he jokingly apologised for. When the Cybermen asked if he was surrendering, he responded that he was surrendering unto them "a very good idea". (TV: Doomsday)
In the 22nd century, the Daleks recovered a burnt piece of paper from the wreckage of a human spaceship, the Starmaker, which revealed to them the location of Earth. The Dalek Emperor decreed that the Daleks would search for and conquer the planet. (COMIC: The Road to Conflict)
At a later stage of the 22nd century, paper had been replaced by holographic slides. (PROSE: Fear Itself) By the end of the 26th century, a shortage of reliable memory and storage devices after the wars resulted in the use of paper again. (PROSE: Tears of the Oracle) By the 30th century, paper hadn't been used for centuries. (PROSE: Just War)
To demonstrate the cause of the stalemate of the Dalek-Movellan War, the Fourth Doctor and Romana played a game involving hand shapes forming "stone", "paper" and "scissors"; paper was represented by a flat hand. (TV: Destiny of the Daleks)
When the Tenth Doctor and Donna Noble arrived at the Library and were surprised to find that, despite no one being visible, 1,000,000,000,000 life forms were detected there, Donna suggested that the books might be alive. (TV: Silence in the Library) They weren't books, but in fact the Vashta Nerada, who were hatched in the Library's books, using them in place of a forest. (TV: Forest of the Dead)
Psionic Paper was a paper that was created by the Paparians. It could create an artificial reality. Whatever the writer wrote down came to life. (AUDIO: Wraith World)