Congestion not only represents a cardinal sign of heart failure but is also now recognized as the primary cause for hospital admissions, rehospitalizations, and mortality among patients with acute heart failure. Congestion can manifest through various heart failure phenotypes in acute settings: volume overload, volume redistribution, or both. Recognizing the congestion phenotype is paramount, as it implies different therapeutic strategies for decongestion. Complete decongestion is hardly achieved among patients with acute heart failure, as more than half still have residual congestion at discharge. Residual congestion is one of the strongest predictors of future cardiovascular events and poor outcomes. Through this review, we try to provide a better understanding of the congestion phenomenon among patients with acute heart failure by highlighting insights into the pathophysiology mechanisms behind congestion and new diagnostic and management tools to achieve and maintain efficient decongestion.