An insurer is one who agrees to pay for specific financial losses to another party through a legal contract. The insurer is only responsible for the losses that are agreed upon in the contract before they actually occur. Typically, insurers are large companies, but individuals can be insurers as well. The party who is using the services of the insurer usually has to pay a "premium" or a scheduled fee to retain the insurance that is being offered.
The basic function of an insurer is to provide insurance. People often seek insurance when they perceive that financial losses in a certain area could be too large to cover themselves. For example, people frequently buy car insurance because damages for car accidents can easily run into the hundreds of thousands of dollars. Other areas where the services of insurers are commonly sought include medicine, dentistry, and property. In all of these areas, insurers can help people hedge against any extreme financial losses in the event of an accident or something else going wrong.