The Preferences API -- a lightweight, cross-platform persistence API introduced in JDK 1.4 -- is designed to store small amounts of data (string, simple byte arrays, and so on.) and was not intended to be an interface to a traditional database. It can, however, be effective as a storage device if your data can be expressed as simple objects. This article offers an introduction to the API, explains how objects are stored, demonstrates the process in action, and provides a code library to do the work.