The Big Bang Theory was an unexpected hit, becoming one of the most-watched sitcoms of the 21st Century. The series had mixed reviews in its first season, which debuted on CBS in late September 2007. However, audiences soon fell in love with the amiable nerds and their friend, Penny. That popularity helped the show become one of the longest-running sitcoms of all time. The Big Bang theory also played a significant role in bringing nerd culture to the forefront of the mainstream public consciousness.
Source：https://www.cbr.com/how-big-bang-theory-ended-sheldon-leonard-penny/
