The owner of the customer relationship with customers who buy second-level domains. There may be many registrars for a single top-level domain. Registrars maintain detailed customer information in their databases, such as the customer’s contact address, telephone number, and e-mail address. Customers usually manage their second-level domains at the registrar’s Web site, and the registrar updates the registry database when necessary (for example, when a customer renews a domain name).