Non-communicable diseases (NCDs) are diseases that are not transmissible directly from one person to another. They are also known as chronic diseases and tend to be of long duration and are the result of a combination of genetic, physiological, environmental, and behavioral factors. NCDs include Parkinsons disease, autoimmune diseases, strokes, most heart diseases, most cancers, diabetes, chronic kidney disease, osteoarthritis, osteoporosis, Alzheimers disease, cataracts, and others. Most NCDs are non-infectious, although there are some non-communicable infectious diseases, such as parasitic diseases in which the parasites life cycle does not include direct host-to-host transmission. NCDs disproportionately affect people in low- and middle-income countries, where more than three-quarters of global NCD deaths occur. The main types of NCDs are cardiovascular diseases (such as heart attacks and stroke), cancers, chronic respiratory diseases (such as chronic obstructive pulmonary disease and asthma), and diabetes. NCDs are the leading cause of death worldwide and represent an emerging global health security threat. They can affect vulnerability to illness, pathogen performance, and the ability of health systems to handle health threats. Addressing NCDs enhances global economic and health security and supports progress towards the United Nations’ Sustainable Development Goals.