Curdling is a process that occurs when proteins in a liquid, such as milk, clump together and form solid masses. This can happen due to the addition of an acid, like lemon juice or vinegar, or when milk is heated too quickly. The result is the separation of the liquid (whey) from the solid (curds), which is a key step in making products like cheese. In cooking, curdling can be undesirable, especially in sauces or soups, where a smooth texture is preferred. To prevent curdling, it's important to gradually heat liquids and avoid adding acidic ingredients too quickly. Understanding this process is essential for achieving the desired consistency in various recipes.