Costs, insurability, and underwriting
The insurer (the life insurance company) calculates the policy prices with intent to fund claims to be paid and administrative costs, and to make a profit. The cost of insurance is determined using mortality tables calculated by actuaries. Actuaries are professionals who employ actuarial science, which is based in mathematics (primarily probability and statistics). Mortality tables are statistically-based tables showing expected annual mortality rates. It is possible to derive life expectancy estimates from these mortality assumptions. Such estimates can be important in taxation regulation.
The three main variables in a mortality table have been age, gender, and use of tobacco. More recently in the US, preferred class specific tables were introduced. The mortality tables provide a baseline for the cost of insurance. In practice, these mortality tables are used in conjunction with the health and family history of the individual applying for a policy in order to determine premiums and insurability. Mortality tables currently in use by life insurance companies in the United States are individually modified by each company using pooled industry experience studies as a starting point. In the 1980s and 90's the SOA 1975-80 Basic Select & Ultimate tables were the typical reference points, while the 2001 VBT and 2001 CSO tables were published more recently. The newer tables include separate mortality tables for smokers and non-smokers and the CSO tables include separate tables for preferred classes. 
Recent US select mortality tables predict that roughly 0.35 in 1,000 non-smoking males aged 25 will die during the first year of coverage after underwriting. Mortality approximately doubles for every extra ten years of age so that the mortality rate in the first year for underwritten non-smoking men is about 2.5 in 1,000 people at age 65. Compare this with the US population male mortality rates of 1.3 per 1,000 at age 25 and 19.3 at age 65 (without regard to health or smoking status).
The mortality of underwritten persons rises much more quickly than the general population. At the end of 10 years the mortality of that 25 year-old, non-smoking male is 0.66/1000/year. Consequently, in a group of one thousand 25 year old males with a $100,000 policy, all of average health, a life insurance company would have to collect approximately $50 a year from each of a large group to cover the relatively few expected claims. (0.35 to 0.66 expected deaths in each year x $100,000 payout per death = $35 per policy). Administrative and sales commissions need to be accounted for in order for this to make business sense. A 10 year policy for a 25 year old non-smoking male person with preferred medical history may get offers as low as $90 per year for a $100,000 policy in the competitive US life insurance market.
The insurance company receives the premiums from the policy owner and invests them to create a pool of money from which it can pay claims and finance the insurance company's operations. Contrary to popular belief, the majority of the money that insurance companies make comes directly from premiums paid, as money gained through investment of premiums can never, in even the most ideal market conditions, vest enough money per year to pay out claims. Rates charged for life insurance increase with the insurer's age because, statistically, people are more likely to die as they get older.
Given that adverse selection can have a negative impact on the insurer's financial situation, the insurer investigates each proposed insured individual unless the policy is below a company-established minimum amount, beginning with the application process. Group Insurance policies are an exception.
This investigation and resulting evaluation of the risk is termed underwriting. Health and lifestyle questions are asked. Certain responses or information received may merit further investigation. Life insurance companies in the United States support the Medical Information Bureau (MIB) , which is a clearinghouse of information on persons who have applied for life insurance with participating companies in the last seven years. As part of the application, the insurer receives permission to obtain information from the proposed insured's physicians.
Underwriters will determine the purpose of insurance. The most common is to protect the owner's family or financial interests in the event of the insurer's demise. Other purposes include estate planning or, in the case of cash-value contracts, investment for retirement planning. Bank loans or buy-sell provisions of business agreements are another acceptable purpose.
Life insurance companies are never required by law to underwrite or to provide coverage to anyone, with the exception of Civil Rights Act compliance requirements. Insurance companies alone determine insurability, and some people, for their own health or lifestyle reasons, are deemed uninsurable. The policy can be declined (turned down) or rated. Rating increases the premiums to provide for additional risks relative to the particular insured.
Many companies use four general health categories for those evaluated for a life insurance policy. These categories are Preferred Best, Preferred, Standard, and Tobacco. Preferred Best is reserved only for the healthiest individuals in the general population. This means, for instance, that the proposed insured has no adverse medical history, is not under medication for any condition, and his family (immediate and extended) have no history of early cancer, diabetes, or other conditions. Preferred means that the proposed insured is currently under medication for a medical condition and has a family history of particular illnesses. Most people are in the Standard category. Profession, travel, and lifestyle factor into whether the proposed insured will be granted a policy, and which category the insured falls. For example, a person who would otherwise be classified as Preferred Best may be denied a policy if he or she travels to a high risk country. Underwriting practices can vary from insurer to insurer which provide for more competitive offers in certain circumstances.
 Death proceeds
Upon the insured's death, the insurer requires acceptable proof of death before it pays the claim. The normal minimum proof required is a death certificate and the insurer's claim form completed, signed (and typically notarized). If the insured's death is suspicious and the policy amount is large, the insurer may investigate the circumstances surrounding the death before deciding whether it has an obligation to pay the claim.
Proceeds from the policy may be paid as a lump sum or as an annuity, which is paid over time in regular recurring payments for either a specified period or for a beneficiary's lifetime.
 Insurance vs Assurance
The specific uses of the terms "insurance" and "assurance" are sometimes confused. In general, in these jurisdictions "insurance" refers to providing cover for an event that might happen (fire, theft, flood, etc.), while "assurance" is the provision of cover for an event that is certain to happen. "Insurance" is the generally accepted term, however, people using this description are liable to be corrected. In the United States both forms of coverage are called "insurance", principally due to many companies offering both types of policy, and rather than refer to themselves using both insurance and assurance titles, they instead use just one.