*Note: this answer is based on the Insurance Services Office's HO-3 policy.
The dwelling and other structures on the premises are protected on an "all risks" basis up to the policy limits. "All risks" means that unless the policy specifically excludes the manner in which your home is damaged or destroyed, there is coverage. The policy limit for the dwelling is set by the policy owner at the time the insurance is purchased. The policy limit for the other structure is usually equal to 10% of the policy limit for the dwelling.
Losses to your personal property are covered on a "named perils" basis. "Named perils" means that you have coverage only when your property is damaged or destroyed in the manner specifically described in the policy. The policy limit on the coverage is equal to 50% of the policy limit on the dwelling. Limits for the coverage for the additional expenses that the policy owner may incur when the residence cannot be used because of an insured loss is equal to 20% of the policy limit on the dwelling.
The coverage limit on personal liability is determined by the policy owner at the time the policy is issued. The coverage limit on medical payments to others is usually set at $1000 per injured person.