Clinicians are likely to encounter delirium frequently, particularly in inpatient and intensive care settings. However, delirium is underrecognized and undertreated because of its heterogeneous and fluctuating presentation and due to the limitations in resources and training in contemporary clinical settings. Translation of current knowledge about delirium into clinical practice may improve patient care and benefit public health economics. Hence, this review comprehensively discusses the phenomenology and pathophysiology of delirium and its presenting features, risk factors, differential diagnoses, assessment, prognosis, and treatment with antipsychotics; the goal is to facilitate better prevention, recognition, and treatment of delirium. Available research is reviewed, limitations of the research are discussed, and future directions for further delirium research are identified.