A front derailleur is a component of a bicycle's gear system that helps shift the chain between different front gears, or chainrings. It is typically mounted near the bottom bracket and is controlled by a shifter on the handlebars. When the rider wants to change gears, the derailleur moves the chain from one chainring to another, allowing for easier pedaling on various terrains. The front derailleur works in conjunction with the chain, rear derailleur, and shifters to provide a smooth and efficient gear-changing experience. Proper adjustment and alignment of the derailleur are essential for optimal performance, ensuring that the chain shifts cleanly without dropping or skipping.