The Alberta Stroke Program Early CT score (ASPECTS) is a 10-point semiquantitative topographic scoring system developed for the assessment of early ischemic changes (EICs) on noncontrast-enhanced computed tomography (NCCT) in patients with acute ischemic stroke involving the middle cerebral artery (MCA) territory. One point is subtracted from a total score of 10, if an EIC is present in any part of each of the ASPECTS regions. Higher ASPECTS has been associated with better outcomes and a lower risk of symptomatic intracerebral hemorrhage. To date, there are still controversies regarding the utility of ASPECTS for selecting patients for intravenous and intra-arterial therapies. This article provides a comprehensive review regarding methodology, limitations, and interobserver reproducibility of ASPECTS, as well as application of ASPECTS in clinical care. The focus of this review is ASPECTS evaluation on NCCT. The application of ASPECTS on multimodal computed tomography and magnetic resonance imaging (MRI) is briefly described.