The book gathers the necessary scientific knowledge for the structure, function, design, and calculation of various hydraulic circuits and systems applied in all modern machines that use high-pressure hydraulic energy as a working medium. With simplicity and clarity, it provides students and professional technical engineers with comprehensive knowledge based on international standards, enabling them to construct or repair simple applications of a hydraulic circuit. Its sixteen chapters include the basic definitions of fluids, the fluids of hydrostatic transmissions, the components of a hydraulic vehicle, the types of hydraulic pumps, the classification of hydraulic valves, the flow control hydraulic valves, hydraulic cylinders, hydraulic motors, hydrostatic closed circuits, hydraulic accumulators, hydraulic fluid filters, and applications of hydrostatic circuits. Finally, the connections of hydraulic circuits and the connections of hydraulic circuits and systems are examined.