RELIGIONS
A multitude of religions are followed by different cultures and peoples throughout the known world. These can range from widespread belief systems followed by great numbers of people, to more localized faiths followed only by a select group. Individual religious devotion in all societies is, of course, on a spectrum, from devout adherents to those that just go through some of the motions by rote as a cultural norm. Some people are also irreligious and privately don't believe in any gods or religious systems.
For more about the religions of Westeros and Essos, including ones not represented in the series, visit here.