This document provides an overview of insurance. It discusses how insurance works by pooling funds from many insured entities to pay for losses some may incur. It also describes key concepts like insurable risk, indemnification, and the business model of insurers which involves underwriting policies and investing premiums to pay claims. The document outlines different types of insurance and principles like affordability and calculability of risk that make something insurable. It also discusses effects of insurance on risk taking and society.