Holobook was a social media service made available through the HoloNet. Members of Holobook could create their own personal profiles listing information such as their homeworld and current status, post photos, make friends with other members and share messages which were available for viewing to anyone who had been added as a friend. A number of added friends could be chosen as "top friends."
Holobook was introduced for use by students at the Jedi academy on Coruscant in Roan Novachez's second year of attendance. Though Roan arrived early for the start of the term, he did not set up a profile right away because he couldn't figure out how and eventually decided he didn't really need to as he could simply use holomail to keep in touch with people. He changed his mind, however, when Gaiana got upset over not being able to select him as a "top friend" on her profile.
Roan soon created his profile and enjoyed sharing jokes with his friends there, as well as updating his status, but was often left mean and bullying comments by Cronah and Cyrus. The two Zabrak Jedi Padawan regularly made fun of Roan and saw Holobook as an easy way to extend the scope of their bullying. Later in the term, when Roan briefly became friends of a sort with the two, he joined them in posting such comments on Holobook profiles. Yoda, upset by the Padawans' behavior and warning that such behaviors were a path to the dark side, temporarily shut down all student access to Holobook. Following a Lightsaber Fencing Tournament, Yoda turned access back on to celebrate, but Cronah and Cyrus were denied access for the time being due to their past bullying behavior and having been caught stuffing the class pet, Voorpee, in a locker.
Holobook is similar to social networking sites such as Facebook, which in real life provides all of the same functions offered by Holobook. The bullying both suffered by and engaged in by Roan is referential of the cyberbullying phenomenon.
In 2020, the Star Wars fan-club "SithCult" developed an open-source social media called Holobook.