In marketing, the ability to track new customers and to link transactions over time is key. Loyalty programs are the most common way for such tracking. Besides, credit card, IP address, and registered user log-ins are also commonly used. Companies also have much better measures that links customer shopping/transaction data with marketing insight such as demographic data from credit card usage, survey data that is linked via email address, store visit information that can be tracked in a variety of ways or from a Customer Relationship Management.