This paper aims to contribute to the internationalization literature by explaining which forms of nonlinear internationalization firms can experience. It explains that nonlinear internationalization can occur in terms of markets, customers, products, sales channels and foreign operation modes. The paper concludes that internationalization should not be only studied in terms of a firm's activities by each market but also by its activities by each sales channel, product, customer, and foreign operation mode in each market. Even if total sales continue increasing in a specific market, this does not mean that the firm has not experienced nonlinear internationalization.