What is primary insurance versus excess insurance?

A primary insurance policy, like a general liability policy, kicks in first to cover a claim or loss. Excess insurance, like an umbrella policy, provides additional coverage for the same claim once the limits of the primary policy have been reached. For example, if you are found liable for $125,000 and your primary insurance policy has a $100,000 limit, an umbrella policy may cover the remaining $25,000.