Corporate earnings refer to the profit a company makes after subtracting all its expenses from its total revenue. This figure is crucial for investors as it indicates the financial health and performance of a business. Companies typically report their earnings quarterly, providing insights into their profitability and growth potential. Earnings are often expressed in terms of earnings per share (EPS), which divides the total earnings by the number of outstanding shares. This metric helps investors compare the profitability of different companies, such as those in the S&P 500 index, and make informed decisions about buying or selling stocks.