A slasher film is a subgenre of horror films in which a killer typically stalks and murders a group of people using a sharp tool or weapon. The subgenre rose to prominence in the late 1970s and early 1980s, although it drew inspiration from the earlier psychological horror of Alfred Hitchcock and Italian giallo films of the 1960s. Slasher films were often low-budget and critically reviled for their shocking depictions of violence. However, after the success of The Texas Chainsaw Massacre (1974) and Halloween (1978), slasher films flourished in American cinema until the mid-1980s. In 1984, A Nightmare on Elm Street helped to revive interest in the genre by introducing supernatural elements into the slasher narrative. By the 1990s, slasher films began to demonstrate metafictional and self-aware attributes, notable in films such as Scream (1996) and I Know What You Did Last Summer (1997). Slasher films typically feature a group of people being pursued by a masked killer with an unusual weapon due to some past wrongful action. The killer is often a villain protagonist and a main perspective character, and franchises tend to follow their continued exploits rather than the stories of the victims.