In linguistics, an example is an expression in some language that has the function of illustrating a statement or concept. The statement or concept may be relatively abstract; the example then renders them more concrete and shows how they are meant to be operationalized, i.e. to be matched with linguistic phenomena. To this end, the example will prominently display exactly those features which are at issue in the statement or essential for the concept, contextualized to the extent necessary. Contrariwise, it will be stripped of such features which are immaterial to the argument and would only distract or confuse the reader who actually needs the example in order to understand.

Data and examples have different functions in linguistic discourse:

• Data have a function in scientific methodology: they are used as evidence to back a scientific statement.
• Examples have a function in didactic communication; they are used to illustrate a general statement or concept by a concrete case falling under it.

In principle, an example can be a piece of linguistic data. It will then usually be a piece of secondary data, since the spatio-temporal coordinates of a particular speech event are seldom relevant in an example. Secondary data are still data, i.e. objects which do not owe their properties to the person who uses them to back a claim. The author is not free to adapt a piece of data to better fulfill its function as an example and yet to present it as a piece of data. For this reason, many linguistic examples are not data, but made up by the author. This is typically the case in textbooks, but is also common in scientific treatises. Such examples are not linguistic data. This does not mean that they would not be allowable. A constructed example may fulfill its demonstrative function much better than any available piece of data. Again, if an author uses a linguistic expression as an example rather than for scientific proof, it makes no sense to require a source for the example.

Since the last third of the twentieth century, it has become more and more customary in linguistics to mark the difference between data and examples in some formal way. In particular, since the functions of scientific proof and of didactic illustration are often combined in a scientific treatise, an example may be marked for its status as a piece of data. To this end, it is provided with a reference to its source. The source itself is listed in detail, and the reader may check whether it represents actual speech events. Contrariwise, if an example is presented without such a reference, the reader expects that it was made up by the author.