Background: Unipolar major depression is commonly encountered in everyday clinical practice, especially in the primary-care setting. Its presentation is very variable, making missed diagnoses a common occurrence; with much dire consequence (e.g. suicide), careful examination of suspected cases and correct identification of affected patients becomes ever so important, not only to specialists but also to general practitioners, whom the majority of cases will present to. Unipolar major depression is a chronic, lifelong disease with a high recurrence rate and worsening prognosis with repeated episodes; therefore, appropriate, timely management in addition to patient education and guidance of their expectation is key to improving clinical outcomes and patient satisfaction. Methodology: The PubMed database and the MeSH tool were employed to collect the articles used in this review. Relevant articles were obtained, if possible, and reviewed. Objectives: Our goal was to perform a comprehensive review of recent review articles that examined unipolar major depression in adults in addition to etiology, epidemiology, pathogenesis, clinical features and types, diagnosis, management, or prognosis. Conclusion: Unipolar major depression is a common mental health problem presenting to the primary-care setting, with many missed diagnoses due to heterogenous presenting features. Management options include psychological therapy, pharmacological therapy, or a combination of both. Early detection and treatment considerably improve the clinical outcome; therefore, it’s imperative that physicians, whether specialists or general practitioners, familiarize themselves with its clinical picture.