Deductible
Deductibles are typically used to deter the large number of claims that a consumer can be reasonably expected to bear the cost of. By restricting its coverage to events that are significant enough to incur large costs, the insurance firm expects to pay out slightly smaller amounts much less frequently, incurring much higher savings. As a result, insurance premiums are typically cheaper when they involve higher deductibles. For example, health insurance companies offer plans with high premiums and low deductibles, or plans with low premiums and high deductibles. One plan may have a premium of $1,087 a month with a $6,000 deductible, while a competitive plan may have a premium of $877 a month with a $12,700 deductible. The consumer with the $6,000 deductible will have to pay $6,000 in health care costs before the insurance plan pays anything. The consumer with the $12,700 deductible will have to pay $12,700.
Vehicle insurance in the United States
Uninsured/Underinsured coverage, also known as UM/UIM, provides coverage if an at-fault party either does not have insurance, or does not have enough insurance. In effect, the insurance company pays the insured medical bills, then would subrogate from the at fault party. This coverage is often overlooked and very important. In Colorado, for example, it was estimated in 2009 that 15% of drivers were uninsured. 
Usually the limits match the liability limits. Some insurance companies do offer UM/UIM in an umbrella policy.