A Pocket Query is a custom Geocache search that can be downloaded and used with software to load caches that fit the criteria of the search.  In clearer words: You can ask for a list of Geocaches that are easy to find (Difficulty 1) and are within 10 miles of your home, for instance.

This is a Premium Membership feature at Geocaching.com.

Here’s what you do:

1. Connect your GPSr to your computer.
2. Logon to Geocaching.com
3. Click on your Geocacher name at the top right of the screen.
4. Click on Build Pocket Queries along the left side panel.
5. Click on Create A New Query.
6. Complete the Pocket Query form.
7. After you submit the form, the Pocket Query will run (Choose the same day of the week as the server for immediate results).
8. Click on the Pocket Queries Ready For Download tab on the Pocket Query page.
9. Click on the Pocket Query you submitted and allow the browser to save the .zip file to the default location.
10. Use software such as GSAK to open the file.  Try these too.
11. Go to the GPS menu in GSAK and select Send Waypoints To GPS