influx

Influx is the arrival or inward flow of people, things, or substances into a place or system. The word derives from the Latin influxus, formed from in- meaning “into” and fluere meaning “to flow,” and it is commonly used to describe large or rapid entries rather than ordinary, gradual movement.

In demography and economics, influx is used to characterize sudden increases in population or capital entering a region. Examples include an influx of migrants or tourists, and capital inflows that bring money into an economy through investments or loans. In urban planning and public policy, discussions of influx often focus on the effects on housing, labor markets, infrastructure, and services.

In science and medicine, influx refers to the inward movement of substances across membranes or barriers. Ion influx describes ions entering cells or compartments, and is a key concept in physiology and cellular signaling. In chemistry, influx can denote the entry of reactants or solvents into a reaction environment. In hydrology and meteorology, influx describes water entering a reservoir, lake, or atmospheric layer, influencing levels and dynamics.

Influx is commonly contrasted with efflux, which denotes outward flow or exit. The term can be used in a broad range of contexts, from scholarly analysis of population movements to technical descriptions of material or fluid entry into systems. In everyday language, it often conveys the idea of a sudden or sizable arrival that can have significant consequences for management and planning.