The Front Derailleur shifts the chain on a bike which has more than a single front chainring. Although the design and front derailleurs vary - they follow the same design principles and fulfil the same purpose. They are usually attached to the bike via a clamp or a bracket.
Front Derailleur will wear out at some point - and you can investigate wear and tear by pulling on the lower cage. A worn out front derailleur will require replacement, or you can expect inconsistent and poor shifting. Front derailleurs are different to rear derailleurs and there are mountain bike, e-bike and road bike specific models.