Religion is a cultural system of beliefs, practices and values. It is often associated with the idea of god or gods, and usually involves organized worship, a sacred book, sacred rites and rituals, and a religious community that includes priests, monks and nuns. It may also have a mythology or narrative, a code of behavior, and social structures, including institutions, rules and laws. It is a powerful influence on the culture of many countries, and may even affect political systems.

The term was first used in the 19th century to describe a set of cultural behaviors and practices that could be shared among a group of people. The most popular religions of the world are Christianity, Islam and Hinduism, but there are also Jewish religions, Bahai and Buddhist religions, and Confucianism and Daoism. The five largest religions together are responsible for over half the population of the world, and they are often intertwined with each other, creating a complex web of belief and practice.

There are several definitions of religion, with scholars differing on how broad or narrow the concept should be. The Oxford Dictionary defines it as “belief in and worship of a superhuman controlling power, especially a personal god”. This definition is often criticised because it excludes religions that do not believe in a god or gods but that have other features that make them religious, such as believing in an afterlife or in the concept of moral good or evil.

It is also possible to define religion more functionally, as a system that generates cohesion within societies and gives them meaning and purpose. This approach has the advantage of not excluding religions that do not claim to be divine in origin and therefore can be applied to all cultures.

Many academics have tried to correct a perceived Western bias in the study of religion, with some questioning whether it has any specific meaning outside of the West. Others, such as Wilfred Cantwell Smith, have advocated a more anthropological understanding of religion, looking at the ways in which it is experienced and understood by believers and non-believers alike.

Generally, all religions have at least some aspects in common, such as the fact that they are organised, have a set of rituals and ceremonies, a sacred book or texts, a central figure such as a prophet or saint, a community of specialists such as priests or witches, a way of dealing with death, and social and cultural symbols. Religions vary in their degree of exclusivity, with some limiting access to members of the faith and others actively spreading it.

Anthropologists that support the idea that religions are cultural phenomena tend to think of them in terms of a four-dimensional model, with the three dimensions of the “true, beautiful and good” and the fourth of community. Ninian Smart has suggested adding a fifth dimension to this model, that of material culture, which he suggests is always present in religions, even when it is not explicitly or implicitly acknowledged.