Access restriction mechanisms ensure that users can only access data relevant to their roles or responsibilities. This is commonly implemented through role-based access control (RBAC), discretionary access control (DAC), or mandatory access control (MAC). The principle of least privilege is critical here, ensuring users and processes only have the minimum permissions necessary to perform their tasks. Be ready to familiarize yourself with the terms RBAC, DAC, MAC and ACL in the future.
There are also additional access restrictions that can be applied to systems and data. For instance, the geographic location of the person could be used to check whether or not it should be allowed. Additionally, time of day restricions could be used to disallow any access during non-working hours.