The phrase "big data" often appears in newspapers and magazines these days. It refers to extremely large amounts of data that are being sent from personal computers, smartphones, car navigation systems, IC cards, etc., and then stored in massive data centers.

The progress of information technology has made it possible to both store and analyze huge amounts of data and the costs of doing so is steadily dropping as technology advances. As a result, companies are increasingly utilizing big data to expand their sales. For example, it is possible to identify the gender and age of people and what they buy using electronic money via their smartphones, debit cards, etc. Analyzed data provide corporations with significant clues regarding the needs and tastes of consumers. They can then develop new products and services to meet these needs and increase their business profits.

It is also expected that such data can be used for medicine and agriculture. Information-technology companies believe that the use of big data will bring great changes to various industries. But a major problem is the thorny issue of how to utilize this data while protecting people's privacy.