To continue, an insurance company must pay all claims that its policyholders will suffer in the future, more or less distant, as well as its own costs of management and distribution. This is the balance "claims / premiums" which is vital in the long term. Mutual insurance companies are not distributing dividends can vary their rates for the sole benefit of their contributors. The total amount of claims are by definition unknown in advance, all insurance companies aim to "pool" risks. Imagine 100 people uninsured, with statistically in 100 chance of being injured: one of these people will likely experience difficult to bear financial woes. By cons, if these 100 people mutualise and they each bring a small contribution constituting a common fund, they will be much better protected in the event of a disaster ... This mechanism aims to reduce the variability of losses. The amount of probable losses (plus a safety margin, and expense management company) is paid by the insured (premium).