This data type has no identifiable structure. In turn, structured data is generally available in tabular form.

Unsupervised learning comprises a set of statistical tools intended for use in an environment in which we only have (or use) one set of input variables on a set of n observations/instances. In this sense, we are not interested in prediction, because we do not have an associated response variable.

This refers to a text string that specifies where a resource can be found on the internet.