Pretty Little Liars is an American teen drama mystery thriller television series of 7 seasons developed by I. Marlene King. The series, loosely based on the novel series of the same name written by Sara Shepard, follows the lives of five best friends whose clique falls apart after the disappearance of their leader Alison. One year later, the estranged friends Spencer, Hanna, Aria and Emily are reunited as they begin receiving messages from a mysterious figure named "A" who threatens to expose their deepest secrets.
The series premiered on June 8, 2010, on Freeform and ended on June 27, 2017. After an initial order of 10 episodes, ABC Family ordered an additional 12 episodes on June 28, 2010. The ratings success of the first 10 episodes prompted the book series to be extended beyond the initial eight novels. Since its debut, the series has received mixed reviews from television critics, but remained a relative success for Freeform, garnering a large fandom. The series finale was viewed by an estimated 1.41 million viewers. It had the second-highest rating of any cable TV series that aired that night but received a lukewarm reception from both critics and audiences.