University physicists Leonard and Sheldon know whether to use an integral or a differential to solve the area under a curve. But they don't have a clue about girls. Or dating. Or clothes. Or parties. Or having fun. Or, basically, life. So when a pretty blonde named Penny moves in the apartment across the hall, the guys decide to get an education outside of the classroom. Boys, you have a lot to learn.

This season, Leonard gets a girl. So does Sheldon. Howard drives the Mars Rover into a ditch. Raj woos a terminator. Gorgeous girl-next-door Penny falls under the spell of Age of Conan. And super-smart, ueberconfident Leslie Winkler reduces mere men to spineless jellyfish.

Worlds collide in Season 3! A love affair with Penny has opened a big, wide, wonderful world of romance for Leonard. But Sheldon likes the world just the way it was, thank you. All of which makes for a zany comic triangle with brainy, clueless Sheldon and practical, grounded Penny hilariously vying for the role of hypotenuse.

This season the Big Bang gang’s romantic universe expands. On the rebound from Penny, Leonard falls into the arms of Raj’s sister Priya. Sheldon gets a girlfriend, or rather a friend who is a girl: Amy, a dour neurobiologist who declares herself besties with Penny. Howard and Bernadette heat up. And so do Raj and Bernadette (at least in Raj’s Bollywood daydream).

In season five, Penny and Leonard's relationship is relaunched in full "beta test" mode, while Sheldon, Howard, and Raj discover the feminine mystique is something that cannot be easily graphed or calculated. As Sheldon makes begrudging amendments to his "Relationship Agreement" with his "friend-who-happens-to-be-a-girl" Amy Farrah Fowler, Raj contemplates an arranged marriage, and Howard is all-systems-go for both is NASA space launch and wedding to the spirited Bernadette.

Leonard returns from his North Sea expedition to find that his relationship with Penny involves more beta-testing than he’s ever done in a lab. Howard’s attachment issues with the women in his life in particular and Raj’s social breakthrough with women in general provide more laughs. Bernadette and Amy stand staunchly by the men in their life, even when they’re sitting in marathon role-playing games. Sheldon sees his mom in a totally different way, parties with James Earl Jones, establishes a (sort of) bond with his idol Professor Proton and makes a scientific breakthrough that breaks down before you can say Science Friday.

Sheldon is rescued from his soul-searching cross-country train trip (older but no wiser) and that means The Big Bang Theory gang's all here to spread another gear's cheer as TV's most attended laugh seminar. Enrol in the comic curriculum to observe Leonard's minor surgery, which signals a major catastrophe for Sheldon, Howard's obsession over his mum's relationship with friend-turned-freeloader Stuart and the unexpected results of Penny's technique as a pharmaceutical sales rep. Discover ways to re-create proms not attended or holiday celebrations not especially beloved and play a new game based on Raj's dating life. Savour online fan Fiction by Amy, watch Bernadette take indelicate command of some delicate family matters and, who knows, you might spot a cool special guest or two.

After years of only looking out for himself, Sheldon found Amy Farrah Fowler to be the most patient woman to ever walk the earth, and... they did it! Wedding fever continues in season 11.

Best friends and brilliant physicists Leonard Hofstadter and Sheldon Cooper are geniuses in the lab but socially challenge outside of it. Despite this, Leonard married his beautiful, street-smart neighbour, Penny. And Sheldon, after a long courtship, wed successful neurobiologist Amy. And while aerospace engineer Howard and his adorable microbiologist wife, Bernadette, explore the predicament of being married with two kids, astrophysicist Raj considers a traditional arranged marriage. As the supersmart friends solve quotidian conundrums posed by academia. Family crises and video games, their experiments in domestic bliss never fail to produce hilarious results. But all good theories arrive at a conclusion. The twelfth and final season of "television's perpetual laughter continuum comprises" 24 supercharged episodes that take comedy to the next dimension...and beyond.