Religion is one of the most basic, all-pervasive, and complex aspects of human culture. In general, people can be described as religious when they have a strong belief in a god or gods and participate in rituals that honor these beliefs. Religions often contain a set of moral rules, such as avoiding lying, respecting one’s parents, and not killing.

The study of religion is concerned with the many different ways that people deal with ultimate concerns about life, death, and their relationship to nature, other humans, and supernatural beings. It may also involve the veneration of objects, words, texts, or persons viewed as having divine or spiritual authority. It includes a wide range of practices, from prayer to meditation, from sacrifices to festivals, from marriage to funerals, from music to art to social service.

Religious systems vary greatly in their beliefs, practices, and institutions, but what they all have in common is a set of guiding questions that are important to every person. Religions are a way for people to answer the question of what is the meaning of life and how to live it, which is arguably the central human question.

The answer to this question varies across time and place, as do the methods used to answer it, but there is no doubt that religions have been among the most important factors shaping history in all cultures and societies. They have been instruments of liberation as well as tools of coercion, and they have been a source of both power and conflict.

Despite their flaws, religions have played a key role in the lives of the vast majority of human beings. They provide a framework for moral behavior and a sense of identity which extends beyond the family or tribal group. They establish codes for recognizing others and help people recognize whether the intentions of those around them are hostile or friendly, even in unfamiliar environments. Religions provide worlds of confidence, enabling individuals to recognize who they are and why they exist, how they should behave, and where they are going.

Ordinary language definitions of religion are generally inadequate because they tend to be reductive and fail to capture the complexities of religious phenomena. However, there are several broad categories that can be useful in understanding the diversity of religions. These include: