Which of the following is NOT a key concept in insurance?

The concept of product endorsement is generally not considered a key principle in the foundation of insurance. In the context of insurance, important concepts revolve around the core elements of risk management, coverage, and the obligations of the parties involved in an insurance contract.

Claims represent the demands made by policyholders to receive benefits under their insurance policies, which is fundamental to the insurance process, as it directly ties to how insurance covers risks. Expiration refers to the end of the coverage period of an insurance policy and is a crucial aspect for both insurers and policyholders, as it dictates when coverage has lapsed. Utmost good faith, or "uberrima fides," is a fundamental principle requiring both parties in an insurance contract to deal honestly and disclose all relevant information, ensuring a fair and transparent agreement.

While endorsements can modify an existing insurance policy (like adding coverage), they are considered more of an adjunct or operational detail rather than a core concept central to the practice of insurance itself. Thus, product endorsement does not hold the same foundational significance as the other listed concepts in the context of the insurance industry.