"Jay and Silent Bob were born in Leonardo, New Jersey, in the 1970s, according to Jay and Silent Bob Strike Back. They met as infants in front of Quick Stop Groceries while their mothers shopped inside The Record Rack, which would eventually become RST Video.

Silent Bob's distinguishing features are his heavy smoking, long coat, dark hair, beard, and backwards baseball cap. He was raised Catholic, and is a gadgetry genius. True to his name, Silent Bob rarely speaks, but when he does, he often has something intelligent or clever to say, delivering insightful monologues to the other characters only in appropriate situations (minus one instance where Jay was so oblivious to the obvious clue needed to find a lost orangutan that Silent Bob grabbed him and shouted, "The sign on the back of the car said 'Critters of Hollywood,' you dumb ♥♥♥♥!"): in Clerks II, when Dante complains that the two never say anything intelligent, Jay calls for Silent Bob to "do his thing", to which Silent Bob can only say "I got nothing." Otherwise he relies on hand gestures and facial expressions to communicate. Silent Bob is often annoyed by Jay and when Silent Bob does speak, he will sometimes ridicule Jay, particularly in Chasing Amy (in which Silent Bob gave his longest speech) and in Clerks II (where he points out when he speaks he usually says something intelligent, whereas Jay says something stupid). In Clerks: The Animated Series, Silent Bob is called "Blutarsky", but according to Smith, that was a joke referencing Animal House and he never gave Silent Bob a last name.[1] In Jay and Silent Bob Reboot, he is thin and lost weight.

Jay is thinner and slightly taller than Silent Bob, and has long, blond hair. In several of the later View Askewniverse films, Jay wears a black knit cap. In contrast to Silent Bob, Jay speaks frequently and rudely and often treats people with disrespect or hostility, including Silent Bob. Jay's excessive cursing seems due to influence from his overbearing mother, who is shown continually using profanity in front of him. His first word was "♥♥♥♥". In Clerks, the first film to feature the duo, Jay wears a San Jose Sharks baseball cap. He is also very active in trying to seduce several women.

Kevin Smith has stated that he sees Jay as ambisexual: "Jay—who's always talking about women—is a character a lot of young hetero guys identify with. But I think Jay's really ambisexual. So it's nice to throw them a curveball to open up their perspective a bit. If I can lead a few cats into being a bit more tolerant, I feel pretty good."[2] In issue #2 of the Chasing Dogma comic series, Jay launches into a lengthy and thoroughly impassioned impromptu speech on gay rights and tolerance before he notices Silent Bob's astonished expression and brushes the matter off. In Dogma, 13th Apostle Rufus asserts that Jay masturbates more than anyone else, and that he thinks about men when doing so; in response to Silent Bob's shocked expression, Jay claims merely that he does not 'always' think of men while whacking off. Moreover, in the prison scene in Clerks II, Jay wants Dante and Randal to fellate each other in exchange for Silent Bob and him loaning them the money to reopen the Quick Stop and RST. He may say this merely to get Dante and Randal to humiliate themselves, but after Silent Bob's disgusted look, he retracts the demand. In a cut version of the same scene, Silent Bob tells Jay that he is a deeply repressed gay man."