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.

The conceptualization of tradition, as the notion of holding on to a previous time, is also found in political and philosophical discourse. For example, it is the basis of the political concept of traditionalism, and also strands of many world religions including traditional Catholicism. In artistic contexts, tradition is used to decide the correct display of an art form. For example, in the performance of traditional genres (such as traditional dance), adherence to guidelines dictating how an art form should be composed are given greater importance than the performer's own preferences. A host of factors can exacerbate the loss of tradition, including industrialization, globalization, and the assimilation or marginalization of specific cultural groups. In response to this, tradition-preservation attempts and initiatives have now been started in many countries around the world, focusing on aspects such as traditional languages. Tradition is usually contrasted with the goal of modernity and should be differentiated from customs, conventions, laws, norms, routines, rules and similar concepts.

The English word tradition comes from the Latin traditio via French, the noun from the verb tradere (to transmit, to hand over, to give for safekeeping); it was originally used in Roman law to refer to the concept of legal transfers and inheritance. According to Anthony Giddens and others, the modern meaning of tradition evolved during the Enlightenment period, in opposition to modernity and progress.

As with many other generic terms, there are many definitions of tradition. The concept includes a number of interrelated ideas; the unifying one is that tradition refers to beliefs, objects or customs performed or believed in the past, originating in it, transmitted through time by being taught by one generation to the other, and are performed or believed in the present.

Tradition can also refer to beliefs or customs that are prehistoric, with lost or arcane origins, existing from time immemorial. Originally, traditions were passed orally, without the need for a writing system. Tools to aid this process include poetic devices such as rhyme, epic stories and alliteration. The stories thus preserved are also referred to as tradition, or as part of an oral tradition. Even such traditions, however, are presumed to have originated (been "invented" by humans) at some point. Traditions are often presumed to be ancient, unalterable, and deeply important, though they may sometimes be much less "natural" than is presumed. It is presumed that at least two transmissions over three generations are required for a practice, belief or object to be seen as traditional. Some traditions were deliberately introduced for one reason or another, often to highlight or enhance the importance of a certain institution or truth. Traditions may also be adapted to suit the needs of the day, and the changes can become accepted as a part of the ancient tradition. Tradition changes slowly, with changes from one generation to the other being seen as significant. Thus, those carrying out the traditions will not be consciously aware of the change, and even if a tradition undergoes major changes over many generations, it will be seen as unchanged.

There are various origins and fields of tradition; they can refer to: