There are five basic legal principles of insurance that must be seen to apply before the policy is valid - Insurable Interest, Indemnity, Umberrima Fides, Subrogation and Contribution.
Umberrima Fides - This phrase is Latin for 'utmost good faith'. This means that the insured must fully disclose all material facts relating to the risk. A material fact is one such as might influence the insurer in either accepting the risk or not, or cause him to charge a higher premium.
It is especially important to be aware that if the insured, or his agent/broker, signs an insurance proposal form declaration stating that the facts therein are true, that the policy can be declared void if there are any inaccuracies, be they material facts or not.