"Giallo" films are characterized by extended murder sequences featuring excessive bloodletting, stylish camerawork and unusual musical arrangements. The literary whodunit element is retained, but combined with modern slasher horror, while being filtered through Italy's longstanding tradition of opera and staged grand guignol drama. They also generally include liberal amounts of nudity and sex.
Gialli typically introduce strong psychological themes of madness, alienation, and paranoia. For example, Sergio Martino's Your Vice Is a Locked Room and Only I Have the Key (also known as Eye of the Black Cat) was explicitly based on Edgar Allan Poe's short story "The Black Cat".
They remain notable in part for their expressive use of music, most notably by Dario Argento's collaborations with Ennio Morricone and his musical director Bruno Nicolai, and later with the band Goblin.http://en.wikipedia.org/wiki/Giallo
There are literally scores of gialli out there - some are brilliant examples of the genre, some enjoyable trash and others that are just plain shite. Which are the films that have you coming back for more? Here are some of my favourites, in no particular order:
The Bird With The Crystal Plumage (1969, Dario Argento)
Deep Red (1975, Dario Argento)
A Lizard In A Woman's Skin (1971, Lucio Fulci)
Don't Torture A Duckling (1972, Lucio Fulci)
Who Saw Her Die? (1972, Aldo Lado)
House With The Laughing Windows (1976, Pupi Avati)
Bay Of Blood (1971, Mario Bava)
The Bloodstained Butterfly (1971, Duccio Tessari)
All The Colours Of The Dark (1972, Sergio Martino)
What Have They Done To Your Daughters? (1974, Massino Dallamano)