<p>Fluid management is a&#xa0;fundamental component of intensive care treatment and has a&#xa0;major impact on the hemodynamics, organ perfusion, tissue oxygenation and prognosis of critically ill patients. This review article outlines the current diagnostic strategies for assessing the volume status using clinical parameters, laboratory markers, imaging techniques and advanced hemodynamic monitoring. In addition to static measurements, dynamic tests such as the passive leg raising test, fluid challenges, respiratory-induced stroke volume variations and end-expiratory occlusion maneuvers for identification of fluid responsiveness are presented. Furthermore, evidence-based recommendations on disease and phase -oriented fluid therapy are discussed. Particular emphasis is placed on the selection of infusion solutions. Balanced crystalloids are recommended as first-line therapy due to their physiological composition and favorable outcome data compared with 0.9% saline. The role of human albumin, especially in septic shock and patients with liver cirrhosis, is critically reviewed based on recent trials. Synthetic colloids are not recommended because of their side effect profile. An optimal fluid management in the ICU requires continuous reassessment, the integration of dynamic monitoring tools and adherence to patient-centered, evidence-based choice of infusion fluid and its amount to improve outcomes in critically ill patients.</p>