Personal information is information about an identified individual, or an individual who is reasonably identifiable.
Some examples of personal information are a person's name, mailing address, email address, phone number, credit information, photographs, IP addresses, location information, employee records, and can also include sensitive information (information or opinion about a person's race, ethnic origin, political views, religious or philosophical beliefs, criminal records, health or genetic information, sexual orientation, or trade union membership or associations).
From this list it is clear to see that most businesses would hold personal information about clients, customers and suppliers.