In her original adventures during the Silver Age, Batgirl is depicted as a librarian by day, and a spirited, if inexperienced, crimefighter by night. After a handful of guest appearances in Batman stories, she was given her own back-up strip in Detective Comics. This allowed the character to be fleshed out considerably, with the shy, mousey, bookworm version of Barbara Gordon quickly giving way to a more modern, confident character. Devoid of her plain-Jane glasses and hair bun, Barbara starts to date what would be a succession of boyfriends, the most popular being Vietnam veteran turned private investigator Jason Bard.
Barbara proved to be more popular than her predecessor (Bette Kane, the Bat-Girl), as readers requested for her to appear in other titles. In addition to her appearances in both Detective Comics and Batman, Batgirl made a guest appearance in World's Finest Comics where she met Superman, Supergirl, Bat-Mite, and Mxyzptlk for the first time. She also fights alongside the Justice League of America against the villainous Queen Bee. She encounters Supergirl again in Adventure Comics #381 when both heroines separately investigate a female criminal gang.
In Batman: The Killing Joke, a graphic novel by Alan Moore and Brian Bolland, the Joker, as part of his plan to drive James Gordon into madness, shoots Barbara through the spine, paralyzing her and ending her career as Batgirl forever.
Initially, Barbara's paralysis plunges her into a period of depression. Eventually, she realizes that, in a world increasingly centered on technology and information, she had a tremendous repository of skills which could be potentially useful to fight crime. These qualities include a genius-level intellect, a photographic memory, a vast knowledge of computers and electronics, expert skills as a hacker, and her training as a librarian.
After having a dream where Barbara (in her previous Batgirl persona) sees an all-knowing woman (similar to Oracle at Delphi of Greek mythology), she adopts Oracle as her new codename. She now acts as an information broker, gathering and disseminating intelligence to law enforcement organizations and members of the superhero community. She has also trained under the tutelege of Richard Dragon, one of the world's premier martial artists, who has trained some superheroes, to engage in combat (usually escrima) from her wheelchair should the need arise.
Barbara first uses the Oracle identity to assist her father on an extremely difficult murder investigation, and later takes it to the Suicide Squad. For a time, she relocates to Belle Reve prison in Louisiana to work with the team under the alias of "Amy Beddoes". After leaving the Suicide Squad, she returned to Gotham City and begins aiding Batman and his protegés frequently, as well as many other heroes. Just after her debut as Oracle in the pages of the Suicide Squad, Barbara appeared in the 12-issue mini-series The Hacker Files. This was her second appearance as a hacker in the DC Comics universe.
Later she joins the Justice League of America, and was an active member for some time, serving as both an information and communications resource. She is currently on inactive status with the group. In mainstream DC continuity, an alternate-reality Batgirl/Barbara Gordon was granted posthumous honorary membership in the League after she sacrificed herself to defeat Hal Jordan (a.k.a. Parallax). Therefore, two Barbara Gordons are members of the Justice League.