Thesauri, Subject Headings and Word Lists are generally used to aid the retrieval of resources, whereas Classifications tend to be for organising resources.<br />
Authority Lists help to standardise the expression of values used in metadata elements, for example in the way dates and proper names are entered. Although there are overlaps, broadly, each serves a different purpose in helping to control the terminology used within metadata schemas and in aiding the search and retrieval of digital resources.<br />
This directory can be used on its own, however it is also a companion peice for Jisc Digital Media's Metadata infokit, and readers are urged to familiarise themselves with the basic concepts of metadata highlighted in that resource. The final section of the Metadata infokit has a discussion on the background and aims of using controlled vocabulary."