In classification, one of the distinguishing characteristics of a class, identified as a means of differentiating it from other classes. As defined in FRBR (Functional Requirements for Bibliographic Records), one of a set of characteristics enabling users of information to formulate queries and evaluate responses when searching for information about a specific entity. Attributes can be inherent in the entity (physical characteristics, labeling information, etc.) or supplied by an external agent (assigned identifiers, contextual information, etc.).
For example, the logical attributes of a creative work include its title, form, date of creation, intended audience, etc. As a general rule, a given instance of an entity exhibits a single value for each attribute, but multiple values are possible (a work may be published under more than one title or in more than one form), or a value may change over time (date of publication for serials). Nor is it necessary for every instance of an entity to exhibit all its attributes--some may be appropriate to a specific subtype of the entity, for example, the attribute "coordinates" applicable only to cartographic materials.
In markup languages such as SGML and XML, a named value used to further specify the meaning of an element. For example, in the string
<title type="proper">The Omen</title> the attribute type has the value proper, which further specifies the meaning of the element title.
In geographic information systems (GIS), information about the characteristics of a given feature, usually stored in tabular format and linked to the feature by a unique identifier. For example, the attributes of a lake might include its name, geographic coordinates (latitude and longitude), surface elevation, total area, and maximum and/or average depth.