To stir, shake, or otherwise move a food or mixture vigorously, a basic operation with surprisingly precise purposes in food processing. Agitation keeps solids suspended in liquids, prevents burning on hot surfaces, promotes even heating and cooling, and drives mass transfer in extraction and crystallization. Chocolate conching, yogurt fermentation, and ice cream freezing all depend on controlled agitation at exactly the right intensity: too gentle and the product is uneven, too violent and emulsions break or textures are damaged. Equipment ranges from simple paddles to high-shear homogenizers, each chosen for the shear sensitivity of the product. In sensory testing the word takes on its other meaning, since an agitated panelist scores unreliably, which is why tasting booths are designed to keep judges calm and focused.