Insurance systems must typically deal with two inherent challenges: adverse selection, which affects any voluntary system, and ex-post moral hazard, which http://www.healthinsuranceaffordable.net affects any insurance ideology in which a third party bears higher responsibility for payment, whether that is an employer or the government. Some national systems with compulsory cover utilize systems such as risk equalization and community rating to overcome these inherent problems.
The fundamental concept of health plan is that it balances costs across a large, purposeless sample of individuals (see risk pool)