A Bouquet garni is a bundle of assorted herbs that are usually tied together and used in the preparation of soup, sauces, stock, and stews. The bundle is tied with a string and dipped into the liquid of whatever is being prepared. This releases the flavors of the herbs into the preparation.
The Bouquet garni is never served with the finished dish. Before finalizing the dish it can easily be removed and discarded and that is the primary reason the herbs are tied together.