Heart failure is a significant and growing public health issue in industrialized countries, particularly with aging populations. The definition of heart failure is challenging, as many patients may have asymptomatic disease, such as asymptomatic left ventricular systolic dysfunction. Data on the epidemiology, aetiology, and prognosis of heart failure are primarily derived from five types of studies: cross-sectional and longitudinal surveys, surveys of individuals treated for heart failure, echocardiographic surveys, nationwide studies of hospitalizations, and comprehensive clinical registries. The prevalence of heart failure increases with age, and over the past few decades, it has increased. Studies from the UK, the US, and other countries show that the prevalence of heart failure is higher in older age groups. The incidence of heart failure is less well understood but is generally higher in men and increases with age. Heart failure admissions are a growing global problem, with high rates of readmission and prolonged stays. The cost of managing heart failure is significant, consuming 1-2% of healthcare expenditure in several industrialized countries. Coronary artery disease, often combined with hypertension, is the most common cause of heart failure in Western developed countries. However, the primary cause can be difficult to determine, and many cases have unknown etiology. Prognosis for heart failure is poor, with mortality rates comparable to cancer. Long-term studies show that heart failure-related mortality is high, and the prognosis has not improved significantly over time. The future burden of heart failure is expected to increase due to the aging population and improved survival rates in those with coronary artery disease. Projections from the Netherlands and Australia predict a significant rise in the prevalence of heart failure caused by coronary heart disease.Heart failure is a significant and growing public health issue in industrialized countries, particularly with aging populations. The definition of heart failure is challenging, as many patients may have asymptomatic disease, such as asymptomatic left ventricular systolic dysfunction. Data on the epidemiology, aetiology, and prognosis of heart failure are primarily derived from five types of studies: cross-sectional and longitudinal surveys, surveys of individuals treated for heart failure, echocardiographic surveys, nationwide studies of hospitalizations, and comprehensive clinical registries. The prevalence of heart failure increases with age, and over the past few decades, it has increased. Studies from the UK, the US, and other countries show that the prevalence of heart failure is higher in older age groups. The incidence of heart failure is less well understood but is generally higher in men and increases with age. Heart failure admissions are a growing global problem, with high rates of readmission and prolonged stays. The cost of managing heart failure is significant, consuming 1-2% of healthcare expenditure in several industrialized countries. Coronary artery disease, often combined with hypertension, is the most common cause of heart failure in Western developed countries. However, the primary cause can be difficult to determine, and many cases have unknown etiology. Prognosis for heart failure is poor, with mortality rates comparable to cancer. Long-term studies show that heart failure-related mortality is high, and the prognosis has not improved significantly over time. The future burden of heart failure is expected to increase due to the aging population and improved survival rates in those with coronary artery disease. Projections from the Netherlands and Australia predict a significant rise in the prevalence of heart failure caused by coronary heart disease.