What set The Big Bang Theory apart from the other sitcoms of its era was its equal focus on its characters as on its sketches ...

One of Sheldon’s most famous and annoying quirks is knocking three times and announcing the person’s name before entering a room. ‘Knock, Knock, Knock, Penny… Knock, Knock, Knock ...

Penny's Gift To Sheldon Is Even Sweeter Now ... It took almost a decade for fans to learn the tragic truth behind the knock -- that Sheldon performs it out of a compulsive abundance of caution ...

As Young Sheldon reached its heartfelt series finale, fans bid a bittersweet farewell to Sheldon Cooper’s journey—a story ...