In the last several years, the research and development of high capacity information storage using holographic technology has been actively carried out by many researchers. This has been driven by several factors. First, the availability and performance of components for drives have changed dramatically. Second, low-cost polymeric storage media which meet many requirements for practical drive systems have been developed. Third, new multiplexing technologies which permit very high density storage with simple optical system configurations have been developed. Holographic data storage technologies could satisfy the requirements of the data warehousing and information processing, as well as of the many applications related with the broadband network to meet the demands of internet traffic. In this paper, we show an outline of holographic data storage technologies. Technology contents relate to a system configuration, recording media and signal processing of two-dimensional digital data. We also discuss the future potential of holographic memory.