Past

The past was the set of all events that occurred before a given point in time, preceding one's present, which was itself followed by the future. In regards to time travellers, the concept of past, present and future was relative. Henry Gordon Jago noted that the Doctor made "gutsily gallant peregrinations" into the "prepossessing provocations of the past" as well as the "freakish fascinations of the future". (AUDIO: The Jago & Litefoot Revival)

Following Rose Tyler's trip to the year 5,000,000,000, far in her relative future, the Ninth Doctor noted that it was appropriate for her second trip to be in her relative past. (TV: The Unquiet Dead)

Despite initially accepting that he would take Martha Jones on "just one trip" in the TARDIS, the Tenth Doctor "stretch[ed] the definition" to allow for a trip to her relative past as well as a trip to her relative future. (TV: Gridlock)

The survivors of the New Dalek Empire regarded the progenitor, a long lost piece of technology which contained the DNA needed to create the New Dalek Paradigm, as both their past and their future, which the Eleventh Doctor remarked was "deep for a Dalek". (TV: Victory of the Daleks)

In River Song's World, Charles Dickens promoted his "new Christmas special" on television as involving ghosts and the past, the present and future, all at the same time. (TV: The Wedding of River Song)

While attempting to flee from the sentient oil with Nardole and Bill Potts, the Twelfth Doctor took the TARDIS to the Dalek-Movellan War, which he explained was "the past" to Bill, a native of 2017. (TV: The Pilot)

Behind the scenes
In The Trip of a Lifetime, the Ninth Doctor tells the audience that they will see "ghosts from the past".