It’s a group living in Pasadena, California.
The Players:
Penny (Kailey Cuoco): Is from Nebraska, moved to LA to become an actress, but hasn’t been able to get much work and is a waitress at The Cheesecake Factory. She’s sort of a “Sex and the City” type of gal. After a couple years of traditional sexual tension in a “we both like each other but won’t admit it” way, she and Leonard had a year long relationship before she broke up with him because he said “I love you” and she wasn’t there yet. Despite this, they’re still close friends, and both are at least “in like” with the other one.
Leonard (Johnny Galecki): Physicist, works at CalTech with Sheldon, Raj, and Howard. Is the closest to a “normal” nerd, the “Average Joe PhD” character. Has been taken with Penny since she moved in next door in the pilot. After breaking up with Penny, he started dating Raj’s sister Priya, though she ended up moving back to India and they failed at a long-term relationship.
Sheldon (Jim Parsons): Theoretical physicist at CalTech, roommate of Leonard. Grew up with a stereotypical Christian Evangelical family in east Texas. The “smartest” of the bunch, also the most arrogant. Does not care for human relationships, human etiquette, and the actor playing him says he “could not be more [Aspergers]” even though technically Sheldon is “not crazy, my mother had me tested”. Lives by his own social rules, including having a huge legal agreement called the “roommate agreement” with Leonard, specifying everything from when each can use the bathroom to what temperature the thermostat will be set at. Sheldon has recently entered into something of a non-sexual relationship with “lady friend” Amy, because Sheldon is somewhat asexual and hates human contact of any kind.
Howard (Simon Helberg): An engineer at CalTech. Despite having a Masters in Engineering from MIT, is the only one of the men who doesn’t have Ph.D. Is Jewish, raised by his stereotypical Jewish mother (who’s never actually seen, only heard), and still lives at home with her. Thinks himself quite the ladies man, though is pretty much never able to get a lady – until! Bernadette, a friend of Penny’s, whom he’s now engaged to. Has a “bromance” with Raj.
Raj (Kunal Nayyar): An astronomer at CalTech. Recently, his work hit a dead end, now he works for/helps Sheldon. Born and raised in India (and Britain, a bit), his father is a gynecologist and drives a Bentley, and Raj had servants growing up. Raj has selective mutism, in which he is unable to speak in front of women, unless he is inebriated (placebos included). Has a “bromance” going on with Howard.
Bernadette (Melissa Rauch): Getting her doctoral in microbiology, she currently works as a waitress at the Cheesecake Factory with Penny. Met Howard on a blind date, they bonded over their issues with their mothers (Bernadette’s being a more Catholic stereotype). Can talk about nerdy stuff with the guys, and then shoes with Penny. Is engaged to Howard, and has moved into his mother’s house with him for a trial run.
Amy Farrah Fowler (Mayim Bialik): Neurologist (or neurobiologist??). Just as socially awkward as Sheldon, but actually desires friendship, romance, and sexual relationships. Forced her way into Penny’s and Bernadette’s friendship, hoping to have “BFFs”, Penny and Bernadette are finding Amy is growing on them.