A chronic condition is a human health condition or disease whose effects are persistent or otherwise long-lasting, or a sickness that develops over time. When a disease lasts more than three months, it is commonly referred to as chronic. In almost all countries, chronic diseases are now the leading cause of death among people. Chronic diseases can go into remission or relapse, where the disease goes away for a while and then reappears. Periods of remission and relapse are frequently mentioned when discussing substance abuse disorders, which some perceive to be chronic conditions. Chronic diseases are frequently linked to non-communicable diseases, which are characterized by non-infectious causes.