A company that offers insurance policies to the public, either by selling directly to an individual or through another source such as an employee's benefit plan. An insurance company is usually comprised of multiple insurance agents. An insurance company can specialize in one type of insurance, such as life insurance, health insurance, or auto insurance, or offer multiple types of insurance.
Insurance companies can be classified into two groups:

• Life insurance companies, which sell life insurance, annuities and pensions products.
• Non-life, General, or Property/Casualty insurance companies, which sell other types of insurance.
  General insurance companies can be further divided into these sub categories.
• Standard Lines
• Excess Lines

In the United States, standard line insurance companies are "mainstream" insurers. These are the companies that typically insure autos, homes or businesses. They use pattern or "cookie-cutter" policies without variation from one person to the next. They usually have lower premiums than excess lines and can sell directly to individuals. They are regulated by state laws that can restrict the amount they can charge for insurance policies.
Reinsurance companies are insurance companies that sell policies to other insurance companies, allowing them to reduce their risks and protect themselves from very large losses. The reinsurance market is dominated by a few very large companies, with huge reserves. A reinsurer may also be a direct writer of insurance risks as well.
Captive insurance companies may be defined as limited-purpose insurance companies established with the specific objective of financing risks emanating from their parent group or groups. This definition can sometimes be extended to include some of the risks of the parent company's customers. In short, it is an in-house self-insurance vehicle. Captives may take the form of a "pure" entity (which is a 100% subsidiary of the self-insured parent company); of a "mutual" captive (which insures the collective risks of members of an industry); and of an "association" captive (which self-insures individual risks of the members of a professional, commercial or industrial association). Captives represent commercial, economic and tax advantages to their sponsors because of the reductions in costs they help create and for the ease of insurance risk management and the flexibility for cash flows they generate. Additionally, they may provide coverage of risks which is neither available nor offered in the traditional insurance market at reasonable prices.