This book unites two symposia from the 2003 MRS Fall Meeting in Boston to address data storage. As the size of material objects approaches nanometer dimensions, the material's structural and electronic properties change. The investigation of factors such as quantum size effects and the impact on next-generation recording media will become even more crucial in the near future, when recording densities approach Terabit/square inch. Therefore, the development of novel instrumentation to explore physical properties at these length scales are becoming more important. Results published here from Symposium GG, Advanced Characterization Techniques for Data Storage Materials, feature characterization techniques including imaging, manipulation and chemical imaging of magnetic, phase change and oxide materials. Symposium HH, Phase Change and Nonmagnetic Materials for Data Storage, gathers researchers working on materials issues related to electronic and optical phase change storage media. From a materials perspective, similar issues are researched in both types of storage technologies. The results published here focus on both applied and fundamental aspects of storage properties.