River Song's diary

River Song kept a diary of her adventures with the Doctor. The cover was TARDIS blue and resembled the exterior of the Doctor's TARDIS. Since the diary was written from River's point of view, she didn't let the Doctor read it, teasingly saying "spoilers!" and often putting her finger on her lips.

The book acted as an indicator of where the Doctor was in his personal timeline; whenever River met him, she would name events she had experienced with him to see if he had experienced them yet. The Eleventh Doctor, in his personal future, explained the purpose of the diary to her; she had no clue what it was supposed to be for until then.

History
Upon saving the Doctor's life (after nearly killing him herself) by giving up her remaining regenerations, River ended up in the best hospital in the universe. It was there that the Doctor gave her the diary. This was done to make sure she kept track of their meetings to keep their timelines from becoming corrupted. (TV: Let's Kill Hitler)

The day after her admission to the hospital, River described that the only things she was left with were a bag of clothes with too many short skirts and her diary. Since pens were not readily available in the 52nd century, the nurses had to order her one from an antique shop so she could write in her journal. Tucked inside the diary she found a business card for Professor Arthur Candy from the Department of Antiquities at Luna University and numbers for a comlink code. (GAME: The Eternity Clock)

While River Song was studying at the Luna University, she did research on the Doctor, and learned a story he was going to die at 5:02pm on 22 April 2011, at Lake Silencio; she recorded this in her diary. (TV: Closing Time)

River brought her diary with her on a trip with the Eleventh Doctor shortly after she had been imprisoned in the Stormcage Containment Facility. The Doctor explained his rules for the diary: River was to use it to keep track of their meetings and adventures together. (TV: First Night)

In the 52nd century, in Stormcage, River was writing about one of her outings with the Doctor before taking a phone call from Winston Churchill and escaping to help her husband. (TV: The Pandorica Opens)

After the Doctor reset the universe at the cost of his own erasure from existence, River temporarily gave her mother her diary as a wedding present to bring him back. Later, the Doctor returned the diary to River, telling her that all the writing had returned, but he hadn't peeked; foreknowledge is dangerous. (TV: The Big Bang)

River spied on the Doctor's first nine incarnations, learning what her husband looked like in his past to help her identify him for their future meetings. However, she ended up getting caught by him before he left Earth with Ian and Barbara. Hearing Susan call for her grandfather, River left, not ready to know if she'll be the mother of one of Susan's parents; she had no clue if this Doctor was one she'd meet. (GAME: The Eternity Clock)

On returning from a trip with the Doctor for her birthday, River met Rory at Stormcage; he wondered if they'd met yet in her timeline, letting River know that he still didn't know she was his daughter. She checked her diary to be sure of where the Doctor was in his timeline. By this point, she'd already been to Demons Run in her past and revealed her identity to the Doctor and her parents. (TV: A Good Man Goes to War)

In 2011, River and an 1103-year-old version of the Eleventh Doctor compared diaries. At this point in his timestream, the Doctor had a similar diary. By this point, she'd visited Easter Island and met Jim the Fish. She seemed fond of Jim when the Doctor mentioned him. (TV: The Impossible Astronaut)

After the crash of the Byzantium, Amy asked River what her diary was. The Eleventh Doctor, who had yet to experience many events recounted in it, told her to stay away from it; he called the diary "her past, my future" before going on to explain their timelines rarely synch up in the right order. (TV: The Time of Angels)

When the Tenth Doctor met River Song for the first time from his perspective, she attempted to "do diaries" with him, naming events which they had experienced together; he did not know who she was. When the Doctor tried to read the diary, River stopped him and told him that, by his own rules, he was not allowed to read it. (TV: Silence in the Library) After the events in the Library and River's death, the Doctor left her diary in the biography section of the Library. Donna Noble and he considered reading it to find out their futures, specifically Donna's (given River's reaction to her identity), but chose not to. By this point in River's timeline, the diary had seen quite a lot of action. Its pages had been heavily written in and weathered. The cover had also become worn, and the spine of the book was now cracked and peeled away slightly from the bindings. (TV: Forest of the Dead)

Alien Records
In addition to adventures, River's diary also contained detailed information on alien creatures including handwritten notes, drawings, photographs, cutouts, and the names and events surrounding various people who have encountered these creatures. These entries include: Weeping Angels, Saturnynians, and Silurians. (WC: Monster Files: Weeping Angels, Monster Files: Vampires, Monster Files: Homo Reptilia) Less detailed alien entries include those of Eight Legs, Zygons, Pakhar, Chelonians, and Raxacoricofallapatorians. (GAME: The Eternity Clock)

Miscellaneous
One diary entry contained notes for piloting the TARDIS, including a drawing of the console, and another was a to-do list prior to River's archaeological expedition of The Library. (GAME: The Eternity Clock)

Recorded adventures

 * One of her first entries, the date of the Doctor's death, though it is possible she was manipulated by the Silents and Madame Kovarian into penning this particular page. (TV: Closing Time)
 * A date with the Eleventh Doctor from an early point in her timeline, where he instructed her to begin using the diary. (TV: First Night)
 * Rebooting the universe. (TV: The Big Bang)
 * The Battle of Demon's Run. (TV: A Good Man Goes to War)
 * A trip with the Eleventh Doctor to Easter Island. (TV: The Impossible Astronaut)
 * An encounter with Jim the Fish. (TV: The Impossible Astronaut, GAME: The Eternity Clock)
 * The crash of the Byzantium. (TV: Silence in the Library)
 * A picnic at Asgard. (TV: Silence in the Library)
 * An adventure in the Bone Meadows. (TV: The Time of Angels)
 * Her second trip to Lake Silencio, 22 April 2011, at the Doctor's invitation. (GAME: The Eternity Clock)
 * Stopping the Eternity Clock from destroying or rewriting time. (GAME: The Eternity Clock)
 * An entry (titled "An Unearthly Mess") in which she got caught by the First Doctor snooping around I.M. Foreman's junkyard in 1963; Susan Foreman is also referenced but not explicitly named. She has other, less detailed entries about meeting other Doctors, second through ninth. (GAME: The Eternity Clock) This is also an oblique reference to the title of the first televised Doctor Who story, TV: An Unearthly Child.
 * A date with the Eleventh Doctor at the Singing Towers of Darillium. This would be her last outing with this particular incarnation before she went to the Library. (TV: Last Night, Forest of the Dead)
 * Her final entry, the expedition to the Library and adventure with the Tenth Doctor, where she gave her life for him. The Doctor left the now obsolete diary in the Library to become part of its collection. (TV: Silence in the Library/Forest of the Dead)