Milestones can be added to Case, Entitlement, and Work Order objects. Cases are typically used to track customer issues, Entitlements manage customer service level agreements, and Work Orders are used in field service operations, all of which can have milestones added to track important events or deadlines within those objects.

To ensure contracted service level requirements are met, the necessary components include entitlement processes to define the steps involved, milestones to track progress, milestone actions to determine what happens at each milestone, and entitlements to specify the SLA terms. Together, these elements will help configure and manage the SLA effectively.