Accidental loss: The event that constitutes the trigger of a claim should be fortuitous, or at least outside the control of the beneficiary of the insurance. The loss should be pure, in the sense that it results from an event for which there is only the opportunity for cost. Events that contain speculative elements such as ordinary business risks or even purchasing a lottery ticket are generally not considered insurable.
Social insurance can be many things to many people in many countries. But a summary of its essence is that it is a collection of insurance coverages (including components of life insurance, disability income insurance, unemployment insurance, health insurance, and others), plus retirement savings, that requires participation by all citizens. By forcing everyone in society to be a policyholder and pay premiums, it ensures that everyone can become a claimant when or if he/she needs to. Along the way, this inevitably becomes related to other concepts such as the justice system and the welfare state. This is a large, complicated topic that engenders tremendous debate, which can be further studied in the following articles (and others):
^ Berger, Allen N.; Cummins, J. David; Weiss, Mary A. (October 1997). "The Coexistence of Multiple Distribution Systems for Financial Services: The Case of Property-Liability Insurance" (PDF). Journal of Business. 70 (4): 515–46. doi:10.1086/209730. Archived from the original (PDF) on 2000-09-19. (online draft Archived 2010-06-22 at the Wayback Machine)
Affordable premium: If the likelihood of an insured event is so high, or the cost of the event so large, that the resulting premium is large relative to the amount of protection offered, then it is not likely that the insurance will be purchased, even if on offer. Furthermore, as the accounting profession formally recognizes in financial accounting standards, the premium cannot be so large that there is not a reasonable chance of a significant loss to the insurer. If there is no such chance of loss, then the transaction may have the form of insurance, but not the substance (see the U.S. Financial Accounting Standards Board pronouncement number 113: "Accounting and Reporting for Reinsurance of Short-Duration and Long-Duration Contracts").
Gap insurance covers the excess amount on your auto loan in an instance where your insurance company does not cover the entire loan. Depending on the company's specific policies it might or might not cover the deductible as well. This coverage is marketed for those who put low down payments, have high interest rates on their loans, and those with 60-month or longer terms. Gap insurance is typically offered by a finance company when the vehicle owner purchases their vehicle, but many auto insurance companies offer this coverage to consumers as well.
Upon termination of a given policy, the amount of premium collected minus the amount paid out in claims is the insurer's underwriting profit on that policy. Underwriting performance is measured by something called the "combined ratio", which is the ratio of expenses/losses to premiums. A combined ratio of less than 100% indicates an underwriting profit, while anything over 100 indicates an underwriting loss. A company with a combined ratio over 100% may nevertheless remain profitable due to investment earnings.
Let's use the aftermath of a major storm to illustrate the differences between collision and comprehensive. Within that storm, let's consider two hypothetical events: First, a heavy telephone pole was blown down and fell on your truck, or second, you swerved to avoid a falling tree and wound up crashing into a guardrail. In the first event, you couldn't control when or why a tree fell on your car. This kind of accident would get reimbursed under your comprehensive policy. In the second situation, you were driving the car and ultimately swerved into the guardrail. This makes it a collision, and collision insurance pays for the damages.