Investment income is a crucial aspect of insurance companies' financial success, as it refers to the earnings they receive from investing their assets. In fact, insurers rely on two sources of income - underwriting and investment income. While the former is the difference between premiums collected and claims paid, the latter can help balance out any losses incurred through underwriting. This is especially important as underwriting operations can often be unprofitable. Therefore, understanding investment income is essential for a comprehensive understanding of the insurance industry.