XML Attribute:

An XML construct that describes an XML Element, or provides additional information about an XML Element and is always given as a name and value pair. An XML Attribute can only have a single value and can only be used once on each XML Element.

In the example below (from a Weave configuration file), id, layer, label and checked are XML Attributes:

<entry id='l_mapengine.main_counciltrees' layer='counciltrees' label='Council Trees' checked='false'/>