A sandbox is an installation provided for the express purpose of providing people with an opportunity to play with software instead of just seeing it from the outside. Both Koha and Evergreen can be seen from the patron point of view by searching demo or live OPACs. The sandbox gets behind the scenes and allows you to see what the staff see. There are also options for testing some of the configuration options.
We now have our own installation of both Koha and Evergreen so circulation staff and systems staff can get behind the scenes and look over the products, kick the tires and try things out. Don't worry about breaking anything, we can always reset it or re-upload test data. This is your opportunity to see what you need to see to start evaluating each product. Imagine if every vendor allowed you to test drive their product before buying it!
We currently have two sandboxes set up. One has Koha installed and that is provided courtesy of ByWater Solutions. Equinox is providing the Evergreen sandbox.