Sheldon's mother Mary refuses to attend his wedding unless he invites his older brother George, with whom he is no longer speaking. Sheldon and Leonard fly to Texas to talk to George, who now owns a chain of tire stores. He refuses to attend and later explains to Leonard and Sheldon that the family sacrificed a lot to fund Sheldon's education, and he was stuck caring for their mother and sister Missy after their father died while Sheldon was in college. Sheldon never thanked him for this. Leonard takes George back to the hotel room where Sheldon apologizes for what he did and the brothers reconcile. George agrees to attend the wedding. Meanwhile, Howard and Bernadette's children contract pinkeye, infecting everyone except Penny, much to Amy's fury.
The show originally centered on five characters living in Pasadena, California: Leonard Hofstadter and Sheldon Cooper, both physicists at Caltech, who share an apartment; Penny, a waitress and aspiring actress who lives across the hall; and Leonard and Sheldon's similarly geeky and socially awkward friends and co-workers, aerospace engineer Howard Wolowitz and astrophysicist Raj Koothrappali. Over time, supporting characters were promoted to starring roles, including neuroscientist Amy Farrah Fowler, microbiologist Bernadette Rostenkowski, physicist Leslie Winkle and comic book store owner Stuart Bloom.
Penny runs into her ex-boyfriend Zack, who has gotten rich from selling his company and married a similarly dim-witted woman named Marissa. Meeting with Leonard and Penny, they say Zack is infertile and ask to pay Leonard as a sperm donor so they can have a baby. Leonard is flattered, but Penny finds it creepy. Leonard says that since Penny decided she did not want to have children, he should be allowed to help another couple with this issue. Sheldon advises him to think about the emotional toll this could have on him. Leonard says he will not do it if Penny objects; Penny says she will support whatever decision Leonard makes. Meanwhile, Raj tries to get Anu back but she points out he just wanted to be married like his friends. Raj points out that Anu is similarly looking for a quick marriage. He admits to Anu that he really likes her and they decide to start their relationship as just dating.
In the third-season finale, Raj and Howard sign Sheldon up for online dating to find a woman compatible with Sheldon and discover neurobiologist Amy Farrah Fowler. Like him, she has a history of social ineptitude and participates in online dating only to fulfill an agreement with her mother. This spawns a storyline in which Sheldon and Amy communicate daily while insisting to Leonard and Penny that they are not romantically involved. In "The Agreement Dissection", Sheldon and Amy talk in her apartment after a night of dancing and she kisses him on the lips. Instead of getting annoyed, Sheldon says "fascinating" and later asks Amy to be his girlfriend in "The Flaming Spittoon Acquisition". The same night he draws up "The Relationship Agreement" to verify the ground rules of him as her boyfriend and vice versa (similar to his "Roommate Agreement" with Leonard). Amy agrees but later regrets not having had a lawyer read through it.
Similar to Kaley Cuoco, Johnny Galecki has been acting since he was young. His first gig was in 1987 — over 30 years ago — and he also starred in National Lampoon’s Christmas Vacation in 1989. He got his big television break on Roseanne and has since become one of the most successful television actors. His impressive resume earned him a net worth of $50 million.
The Big Bang Theory started off quietly in Canada, but managed to garner major success in later seasons. The Big Bang Theory is telecast throughout Canada via the CTV Television Network in simultaneous substitution with cross-border CBS affiliates. Now immensely popular in Canada, The Big Bang Theory is also rerun daily on the Canadian cable channel The Comedy Network.
Penny, who admits to missing Leonard in "The Roommate Transmogrification", accepts his request to renew their relationship in "The Beta Test Initiation". After Penny suggests having sex in "The Launch Acceleration", Leonard breaks the mood by proposing to her. Penny says "no" but does not break up with him. She stops a proposal a second time in "The Tangible Affection Proof". In the sixth-season episode, "The 43 Peculiarity", Penny finally tells Leonard that she loves him. Although they both feel jealousy when the other receives significant attention from the opposite sex, Penny is secure enough in their relationship to send him off on an exciting four-month expedition without worrying in "The Bon Voyage Reaction". After Leonard returns, their relationship blossoms over the seventh season. In the penultimate episode "The Gorilla Dissolution", Penny admits that they should marry and when Leonard realizes that she is serious, he proposes with a ring that he had been saving for years. Leonard and Penny decide to elope to Las Vegas in the season 8 finale, but beforehand, wanting no secrets, Leonard admits to kissing another woman, Mandy Chow (Melissa Tang) while on an expedition on the North Sea. Despite this, Leonard and Penny finally elope in the season 9 premiere.
In March 2017, CBS renewed the series for two additional seasons, bringing its total to twelve, and running through the 2018–19 television season. On August 22, 2018, CBS and Warner Bros. Television officially announced that the twelfth season would be the series' last. This stems from Jim Parsons' decision to leave the series at the end of the season if the show were to have been renewed for a thirteenth season. The series concluded with an hour-long finale consisting of two back-to-back episodes on May 16, 2019. A retrospective, hosted by Johnny Galecki and Kaley Cuoco, aired at 9:30 P.M. ET/PT, the night of the finale, following the season two finale of Young Sheldon.
Warner Bros. Television controls the online rights for the show. Full episodes are available at tv.com, while short clips and recently aired full episodes are available on cbs.com. In Canada, recent episode(s) and pictures are available on CTV.ca. Additionally in Canada, the first six seasons are available for streaming on Bell Media's CraveTV. After the show has aired in New Zealand the shows are available in full online at TVNZ's on demand web service.
When Raj misses out on a job at the planetarium, his father says he has no confidence because Howard always makes fun of him. Raj distances himself from Howard and later gets the job. Howard is hurt by this (even after apologizing to him) and tries to make amends with Raj after his first performance at the planetarium but, when he sees him get a date, he leaves without speaking to him, thinking that the latter's life is better without him. Meanwhile, Sheldon and Amy try randomly dividing up wedding tasks, but they keep arguing. The only thing they can agree on is to get married, so they decide to just get married at City Hall. However, Sheldon decides that he wants a first dance with his new wife and they go home to plan their wedding.