Customer data refers to the information collected and stored by a company about its customers. This can include personal details such as name, address, and contact information, as well as transaction history, purchase preferences, and other relevant data. It is a valuable resource for businesses as it allows them to better understand their customers, tailor their products and services, and improve their overall customer experience. However, it is important for companies to handle customer data ethically and securely, as it contains sensitive information that must be protected.