f17582d2_engine___Free_net_encyclopedia__Type
[Description] First stage compressor greatly enlarged to provide bypass airflow around engine core [Advantages] Quieter due to greater mass flow and lower total exhaust speed, more efficient for a useful range of subsonic airspeeds for same reason [Disadvantages] Greater complexity (additional ducting, usually multiple shafts), large diameter engine, need to contain heavy blades. More subject to FOD and ice damage. Different degrees of bypass are possible - this is the design most commonly used on commercial airliners [Type] 
Turbofan
Jet engine - Free net encyclopedia
Type