We must understand the difference between DATA and INFORMATION.
Information consists of pieces of data that a business can use to identify with 100% accuracy a particular Customer, AND what the business can do to serve the Customer better, and ultimately, increase sales.
In the past, data that was recorded on Customers were limited to Name, Address, Telephone Number, and a unique ID. However, this limited data could not help the business to do more, which means this data was not useful, and simply meaningless to collect and store.
Customer Information is achieved only when the data is ENHANCED, and is needed to help the business to understand who they are dealing with, and how to serve them better.
There are many methods to ENHANCE Customer Data, but it is important to understand that it is not possible to achieve 100%, i.e. many Customers will not be willing to provide more information about themselves. So, the methodology used, the rationale for asking, the incentive offered, and the situation/time are very important to increase the success rate.