Any insurance plan by which a number of employees of an employer (and their dependents), or members of a similar homogeneous group, are insured under a single policy, issued to their employer or the group with individual certificates of insurance given to each insured individual or family. Individual employees may be insured automatically by virtue of employment, only on meeting certain conditions (employment for over a month), or only when they elect to be insured (and usually to make a contribution to the cost of the insurance). Group health insurance is usually experience rated (except for small groups, all of which insured by an individual company in the same area are given the same rate by that company) and less expensive for the insured than comparable individual insurance (partly because an employed population is generally healthier than the general population, and partly because of lower administrative costs, especially in marketing and billing). Note that the policyholder or insured is the employer not the employees.