An entity is defined as anything recognized as being capable of an independent existence and which can be uniquely identified.

In software clustering, an entity may be a class, a source file, a function call statement, or a software module.

An attribute is usually a software artefact, such as a package, a file, a function, a line of code, a database query, a piece of documentation, or a test case. Attributes may also be high level concepts that encompass software artefacts, such as design pattern instances.