An air circulator is a type of fan that is designed to circulate air around a whole room, rather than just blowing it in a specific direction.
For this reason, air circulators are especially effective when combined with a cool air source like an air con unit (here’s more on air con vs fans). In this setup, an air circulator amplifies the work of the air con unit, helping drop the overall temperature in the room far more efficiently and ensuring the cooling air is evenly distributed.
If you don’t have air con, they can still be useful, for example by circulating the breeze from an open window.
Say your bedroom has heated up during a sunny day – if you pop an air circulator next to an open window when night starts to fall and the temperature outside drops, it’ll help distribute that cool air around your room in double-quick time, for a cooler sleep. They’re also good for improving room ventilation.