Prevalence, in the context of studying disorders, diseases, or social phenomena within a population, refers to the total number of cases (both new and existing) of a specific condition or characteristic that exist in that population at a particular point in time or during a specified period. It provides a snapshot of how widespread a condition is within a population at a given time and is often expressed as a proportion or percentage of the population. Prevalence is influenced by both the rate at which new cases occur (incidence) and the duration of the condition. It is a key measure used in public health and sociology to understand the extent of social or health issues and to plan interventions and resource allocation.