The initial premise of the show was based on the adjustment and culture shock that twins Brandon (Jason Priestley) and Brenda Walsh (Shannen Doherty) experienced when they and their parents, Jim (James Eckhouse) and Cindy (Carol Potter) moved from Minneapolis, Minnesota to Beverly Hills. In addition to chronicling the characters' friendships and romantic relationships, the show addressed numerous of topical issues such as sex, date rape, homophobia, animal rights, alcoholism, drug abuse, domestic violence, eating disorders, antisemitism, racism, teenage suicide, teenage pregnancy, and AIDS.
After a poor start in the ratings during its first season, the series gained popularity during the summer of 1991, when Fox aired a special "summer season" of the show while most other series were in reruns. Viewership increased dramatically, and 90210 became one of Fox's top shows when it returned that fall. The show became a global pop culture phenomenon with its cast members, particularly Jason Priestley and Luke Perry, who became teen idols; the series also made actresses Shannen Doherty, Jennie Garth, and Tori Spelling household names in the US. The show is credited with creating or popularizing the teen soap genre that many other successful television shows followed in the years to come.
The show had many cast changes; Jennie Garth, Tori Spelling, Ian Ziering, and Brian Austin Green were the only actors to appear during its entire run and appeared on the first episode of Melrose Place.
The series begins with the introduction of the Walsh family—Jim, Cindy, Brandon, and Brenda—who have recently moved from Minneapolis, Minnesota to Beverly Hills, California as a result of Jim's job promotion. In the first episode, Brandon and Brenda begin attending West Beverly Hills High School, where they befriend several classmates: the self-centered and promiscuous Kelly Taylor, carefree and spoiled Steve Sanders, smart and driven Andrea Zuckerman, ditzy and virtuous Donna Martin, brooding loner Dylan McKay, and younger and naive students David Silver and Scott Scanlon. The show follows the siblings as they bear witness and take part in the dramatic lives that their wealthy and privileged peers lead.
Torand Productions was used by the production company for several seasons on the show. "Torand" is derived from the first several letters of Aaron Spelling's first and second children, Tori and Randy.