Attributes

"Attached to elements", carry "additional info" to elements -- eg. its ID, required formatting (style) in case of (X)HTML, or links to other elements

Conceptually, we could replace all attributes with elements but we keep attributes to maintain readability.

The attribute content is NOT further structured (at least not according to XML standards. An application may see it other way but generally it is not recommended, cf. attributes in relational data model.)

The physical order of attributes in the start tag is NOT important and generally is NOT considered.