Gluten

Gluten is a general name for the proteins found in wheat, barley, and rye. It acts as a binder, giving dough its elastic quality and providing a chewy texture to baked goods like bread and pasta.
Gluten is a common ingredient in many everyday foods:
Grains: Wheat, spelt, farro, barley, rye, and triticale.
Common Foods: Breads, pasta, cereals, and many baked goods.
Hidden Sources: Gluten is also often used as a thickening agent or flavor enhancer in processed foods like sauces, soups, beer, and some packaged products.