The article provides a comprehensive overview of the third universal definition of myocardial infarction (MI) developed by the Joint ESC/ACCF/AHA/WHF Task Force. The definition aims to standardize the diagnosis and classification of MI, which is a major cause of death and disability worldwide. The document emphasizes the importance of distinguishing between different conditions that can lead to MI, such as spontaneous and procedure-related events. It outlines the criteria for diagnosing acute and prior MI, including the use of cardiac biomarkers like troponin and creatine kinase-MB, as well as electrocardiographic (ECG) findings. The article also discusses the role of imaging techniques such as echocardiography, radionuclide imaging, and magnetic resonance imaging (MRI) in diagnosing and characterizing MI. Additionally, it addresses the challenges in diagnosing MI in specific clinical contexts, such as during cardiac procedures, noncardiac surgeries, and in intensive care units. The document highlights the need for careful evaluation and clinical judgment in distinguishing between different types of MI and their implications for treatment and prognosis.The article provides a comprehensive overview of the third universal definition of myocardial infarction (MI) developed by the Joint ESC/ACCF/AHA/WHF Task Force. The definition aims to standardize the diagnosis and classification of MI, which is a major cause of death and disability worldwide. The document emphasizes the importance of distinguishing between different conditions that can lead to MI, such as spontaneous and procedure-related events. It outlines the criteria for diagnosing acute and prior MI, including the use of cardiac biomarkers like troponin and creatine kinase-MB, as well as electrocardiographic (ECG) findings. The article also discusses the role of imaging techniques such as echocardiography, radionuclide imaging, and magnetic resonance imaging (MRI) in diagnosing and characterizing MI. Additionally, it addresses the challenges in diagnosing MI in specific clinical contexts, such as during cardiac procedures, noncardiac surgeries, and in intensive care units. The document highlights the need for careful evaluation and clinical judgment in distinguishing between different types of MI and their implications for treatment and prognosis.