[3] The show originally centered on five characters living in Pasadena, California: Leonard Hofstadter (Johnny Galecki) and Sheldon Cooper (Jim Parsons), both physicists at Caltech, who share an apartment; Penny (Kaley Cuoco), a waitress and aspiring actress who lives across the hall; and Leonard and Sheldon's similarly geeky and socially awkward friends and coworkers, aerospace engineer Howard Wolowitz (Simon Helberg) and astrophysicist Raj Koothrappali (Kunal Nayyar).

[4][5] Over time, supporting characters were promoted to starring roles, including neuroscientist Amy Farrah Fowler (Mayim Bialik), microbiologist Bernadette Rostenkowski (Melissa Rauch), and comic book store owner Stuart Bloom (Kevin Sussman).

The show was filmed in front of a live audience and produced by Chuck Lorre Productions, with Warner Bros. Television handling distribution.

[36] On the evolution of the show, Chuck Lorre said, "We did the 'Big Bang Pilot' about two and a half years ago, and it sucked ... but there were two remarkable things that worked perfectly, and that was Johnny and Jim.

David Saltzberg, a professor of physics and astronomy at the University of California, Los Angeles, checked scripts and provided dialogue, mathematics equations, and diagrams used as props.

[52] The Canadian alternative rock band Barenaked Ladies wrote and recorded the show's theme song, which describes the history and formation of the universe and the Earth.

Co-lead singer Ed Robertson was asked by Lorre and Prady to write a theme song for the show after the producers attended one of the band's concerts in Los Angeles.

Coincidentally, Robertson had recently read Simon Singh's 2004 book Big Bang,[53][54] and at the concert he improvised a freestyle rap about the origins of the universe.

Before production began on the eighth season, the three plus Helberg and Nayyar looked to renegotiate new contracts, with Galecki, Parsons, and Cuoco seeking around $1 million per episode, as well as more back-end money.

The duo, who were looking to have salary parity with Parsons, Galecki, and Cuoco, signed their contracts after the studio and producers threatened to write the characters out of the series if a deal could not be reached before the start of production on season eight.

[68] By season 10, Helberg and Nayyar reached the $1 million per episode parity with Galecki, Parsons, and Cuoco, due to a clause in their deals signed in 2014.

[69] In March 2017, the main cast members (Galecki, Parsons, Cuoco, Helberg, and Nayyar) took a 10 percent pay cut to allow Bialik and Rauch an increase in their earnings.

Star Trek: The Next Generation cast members Brent Spiner and LeVar Burton have had cameos as themselves,[83][84] while Wil Wheaton has a recurring role as a fictionalized version of himself.

On a number of occasions, the group members have dressed up as pop culture characters, including The Flash, Aquaman, Frodo Baggins, Superman, Batman, Spock, The Doctor, Green Lantern, and Thor.

[87] As a consequence of losing a bet to Stuart and Wil Wheaton, the group members are forced to visit the comic book store dressed as Catwoman, Wonder Woman, Batgirl, and Supergirl.

This relationship is jeopardized when Leonard mistakenly comes to believe that Raj has slept with Penny, and it ultimately ends when Priya sleeps with a former boyfriend in "The Good Guy Fluctuation".

Although they both feel jealousy when the other receives significant attention from the opposite sex, Penny is secure in their relationship, even when he leaves on a four-month expedition to the North Sea in "The Bon Voyage Reaction".

However, 45 days into the trip, Sheldon gets mugged and calls for Leonard to drive him home, only to be confronted by Amy, who is upset over not being contacted by him in weeks.

[94] She reflects the Jewish mother stereotype in some ways, such as being overly controlling of Howard's adult life and sometimes trying to make him feel guilty about causing her trouble.

Howard, in turn, is attached to his mother to the point where she still cuts his meat for him, takes him to the dentist, does his laundry and "grounds" him when he returns home after briefly moving out.

[107] In December 2024, it was announced that CBS parent company Paramount Global had acquired non-exclusive cable rights to The Big Bang Theory for Nick at Nite and MTV, beginning December 24, 2024 and January 1, 2025 respectively; Deadline Hollywood reported that the current contract with TBS had made the linear television rights non-exclusive, allowing them to be shared with other broadcasters.

When the third season premiered on September 21, 2009, however, The Big Bang Theory ranked as CBS's highest-rated show of that evening in the adults 18–49 demographic (4.6/10) along with a then-series-high 12.83 million viewers.

[157] During its fourth season, it became television's highest rated comedy, just barely beating out Two and a Half Men (which held the position for the past 8 years).

[212] During its eighth season, The Big Bang Theory shared its 8:30 pm time period with fellow CBS comedy, 2 Broke Girls.

[225] Officially titled Теоретики [ru] (The Theorists), the show features "clones" of the main characters, a similar opening sequence, and what appears to be a very close Russian translation of the scripts.

The prequel series, described as "a Malcolm in the Middle-esque single-camera family comedy" would be executive-produced by Lorre and Molaro, with Prady expected to be involved in some capacity, and intended to air in the 2017–18 season alongside The Big Bang Theory.

[237] The prequel series came to an end on May 16, 2024, with an hour long episode which included George Cooper's funeral and a cameo from Parsons and Mayim Bialik as their older characters.

In January 2024, it was announced that there will be a spin-off series of Young Sheldon focused on Georgie Cooper and Mandy McAllister that will be slated for the 2024–25 season on CBS.

[239] On October 10, 2024, it was announced that the third spin-off will feature Stuart Bloom, Denise, and Bert Kibbler, with Kevin Sussman, Lauren Lapkus, and Brian Posehn reprising their roles.

[241][242] In March 2023, political analyst Mithun Vijay Kumar filed a court case in Mumbai against Netflix due to the series insulting Madhuri Dixit in an episode of season 2 by calling her a "leprous prostitute".