A tradition is a system of beliefs or behaviors (folk custom) passed down within a group of people or society with symbolic meaning or special significance with origins in the past. A component of cultural expressions and folklore, common examples include holidays or impractical but socially meaningful clothes (like lawyers' wigs or military officers' spurs), but the idea has also been applied to social norms and behaviors such as greetings, etc. Traditions can persist and evolve for thousands of years— the word tradition itself derives from the Latin word tradere literally meaning to transmit, to hand over, to give for safekeeping. While it is reportedly assumed that traditions have an ancient history, many traditions have been invented on purpose, whether it be political or cultural, over short periods of time. Various academic disciplines also use the word in a variety of ways.

The phrase "according to tradition" or "by tradition" usually means that what follows is known only through oral tradition and is not supported (and might even be refuted) by solid evidence. Here, "tradition" describes the source or nature of the information. For example, "According to tradition, Homer was born on Chios, but many other places have historically claimed him as theirs." This tradition may never be proven or disproved. Another example is, "King Arthur, according to history, a true British king, has inspired many well loved stories." Whether the claims are supported by evidence or not does not reduce their value as cultural history and literature.

Traditions are subject of study in several academic fields of learning, especially in the humanities and social sciences, including anthropology, archaeology, history, and sociology.