Assembling "reverse phone directories"–databases which link business, residential, and cell phone numbers to their owners' names and personal information—researchers collect personal data from government sources, public information, brokers of marketing data, and other reliable sources. Many local merchants use their directories to personalize their service and grow their business. Many ordinary people use online reverse phone directories to make sure they have correct and up-to-date addresses for stores, services, and friends. Just as importantly, though, with online access to reverse phone directories, people can protect their own privacy. Not everyone wants his or her private data available to the general public. Therefore, reverse directory services allow customers to restrict access to their own information, keeping themselves safe from intrusion, interruption, or worse.