The income statement can also be called a profit and loss statement or operating statement. This is a summary of the income and expenses of a business during a certain period: monthly, quarterly, or annually. If the company has more income than expenses for a certain period it has net income (a profit). If the expenses exceed income, the company has a net loss.
Income can be broken into two broad categories: service income and sales income. The difference between the two lies in the need to consider inventory costs. Service income is derived from performing a service while sales income is derived from selling a product. In general, service companies have staff that perform a service for a customer, while sales companies have product that they sell.
With service income, the profit can be determined simply by deducting expenses associated with performing the service. With sales income, however, you must consider the cost of creating the product (raw materials, labor, overhead, etc.). This inventory cost is referred to as the cost of goods sold.