A "whitelist" is a list of approved items, such as email addresses, IP addresses, or applications, that are granted access to a system or network. This concept is commonly used in cybersecurity to allow only trusted entities while blocking all others. By using a whitelist, organizations can enhance their security by reducing the risk of unauthorized access. In contrast to a blacklist, which identifies items that are explicitly denied, a whitelist focuses on what is permitted. This approach is often applied in various fields, including email filtering, firewall configurations, and application management, to ensure that only safe and reliable sources are allowed.