From The Grindhouse Cinema Database
Giallo translated to English means yellow. It is a reference to the cheap yellow paperback murder-mystery books that were sold in Italy during the mid 20th century. You could even call them Italian "pulp fiction" paperbacks. Giallo is now an expression used to describe the specific Italian subgenre murder mystery thrillers that became popular in the late 60s-70s. The gialli usually involved an unknown killer who preyed on beautiful women. This killer would only be seen in quick shots and the dark mysterious figure would often wear black clothing and gloves. The killer would also use sharp razor blades, butcher knives, ropes and other torturous methods instead of guns to murder his victims.