Why Do Owls Hoot?

Have you ever wondered why do owls hoot? and why do owls only hoot at night time? Owls can sound quite frightening in the middle of the night, but their calls all have their reasons. All hoots were of Barred Owls. Sources of owl noises: https://www.xeno-canto.org/410888 https://www.xeno-canto.org/82754 https://www.xeno-canto.org/363749