Religion is an umbrella term that has been used to describe a wide variety of cultural systems of beliefs, behaviours and ethics. It has also been a subject of philosophical inquiry with many philosophies trying to define the concept in terms of essential qualities and as a social taxon. It has also been a subject of criticism, notably the claims that there is no such thing as religion, or that its modern semantic expansion went hand in hand with European colonialism.

The word religion is a Latin word meaning belief in a god or spirits. It is a general category that encompasses beliefs, practices and traditions of people who believe in a supernatural being or powers. It may also include cosmological orders, or the beliefs that explain the origin and structure of the world and universe. It is an important topic in the history of human culture.

It is also a common theme in philosophy, sociology and theology. The question of what defines a religion is one of the most complex and difficult questions to address. For some scholars, a religion is a set of beliefs and practices that bind people together in a moral community. For others, it is a social institution that provides guidance in life. For still others, it is a set of rituals that express doctrinal beliefs.

A religion can be large-scale and coherently organized, with a hierarchy of the Pope, bishops, cardinals, priests, nuns and laity, and an organization for worship with special holy places and ceremonies. It can be based on personal experiences, or on sacred texts and traditions. It can be based on the ecstatic experience of transcendence, or in the desire for security and guidance in life. It can be based on a sense of spiritual connection with the universe and all its elements, or it can focus on a particular group of beings – human, divine or animal – and their interactions with humans.

In some cases, a religion is a socially constructed system designed to control and discipline its members. It is often based on rules and hierarchies, but it can also be a system of reward and punishment, or simply of recognition and status. In all these ways, it has been a key element in the evolution of human societies and cultures, as well as in their collapse.

The vast range of practices that have been called religions shows that the question of what the term really means is not easily answered. This is a complex issue, and stipulative definitions of religion can be criticised on the grounds that they are too broad or too narrow. For example, a definition that is too broad would include all forms of belief in ghosts or the afterlife; while a definition that is too narrow might be accused of treating only Christianity as a religion and failing to consider faith traditions that emphasize immanence or oneness, such as some versions of Buddhism or Hinduism.