To vent, or not to vent? Venting attaches the hood to a duct, moving the air pulled in by the hood from the kitchen to the outdoors. Recirculating means a fan with no duct, instead using filters in the hood to clean the air that gets pulled in before sending it directly back into the kitchen. SMEG hoods can do both, able to vent out-of-the-box, and able to recirculate with the addition of a filter accessory!