Limits, or Facets, are terms from the metadata (descriptions) of the items in your search results, grouped and counted. Because limits depend on the presence and consistency of the descriptive metadata, they sometimes are not a complete representation of the results.
After you carry out your search, you can choose to use Limits to view only the most relevant results. Limits can be very useful to help you focus your search, and when searching for specific formats such as Music or Cartographic materials.
In the Books Advanced Search, you can choose to can apply some limits before you search.
Example: Differentiate between different authors with the same name:
An Advanced Books Search for the Author John Barton finds over 300 results by several authors with that name.
Use the Author limit to distinguish among the individuals by full name, birth/death dates, other identities, etc.
Example: Limit by Geographic Region:
An Advanced Books Search for the Subject Java finds over 2900 results, most of them about the computer programming language. Use the Geographic Region limit to focus on the island location, Java. Remember that a Geographic Descriptor must be present in the metadata (description of the item) in order for the Limit to be applied. You would want to look at the results for both the Geographic Descriptors Java and Java (Indonesia):