In modern usage, hijab generally refers to various head coverings conventionally worn by many Muslim women. While a hijab can come in many forms, it often specifically refers to a headscarf, wrapped around the head, covering the hair, neck and ears, but leaving the face visible. The use of the hijab has been on the rise worldwide since the 1970s and is viewed by many Muslims as expressing modesty and faith. There is a consensus among Islamic religious scholars that covering the head is either required or preferred, though some Muslim scholars and activists argue that it is not mandated. According to the Harvard University Pluralism Project: "Some Muslim women cover their head only during prayer in the mosque; other Muslim women wear the hijab; still others may cover their head with a turban or a loosely draped scarf."