The paper considers the economic essence of investments and their classification. The author studies the theoretical aspect of the concept of "investment" in accordance with its main characteristics, namely, as an object of economic management, as an alternative opportunity to invest capital in economic activities, as a form of attracting accumulated capital into the economic process. The author identifies common and distinctive features of the concepts of "investment" and "capital investment", in particular, by the following characteristics: purpose of implementation, term of implementation, form of implementation, scope of implementation, risk of capital loss, purpose and source of proceeds. The author identifies the role of investments for business entities, namely, ensuring the competitiveness of products and improving their quality, structural reorganization of production, creation of the necessary raw material base for the efficient functioning of enterprises, and solving social problems. The author classifies investments at an enterprise according to their division into real and portfolio investments. The former includes investments for enterprise development, in particular, for reconstruction and technical re-equipment, for expansion of the enterprise, for production of new products and for modernization of products and development of new resources, and investments for development of the non-industrial sphere, namely, for housing construction, for construction of sports and recreational facilities, and for improvement of working conditions and safety. As for portfolio investments, they are divided into the following two groups: acquisition of securities, in particular, acquisition of shares in other commercial organizations, acquisition of bonds and acquisition of other securities, and investments in assets of other enterprises, namely investments in assets of other manufacturing enterprises and in assets of financial and credit institutions, and investments in assets of other commercial organizations.