In brief
Sifting breaks up lumps and introduces air into a dry ingredient.
Useful to know
Sifting breaks up lumps and introduces air into a dry ingredient. King Arthur explains that not every modern recipe requires it, although it can make even mixing easier in some batters. [1]
Read the measuring order carefully. “Flour, sifted” and “sifted flour” are not necessarily the same volume measurement. If grams are given, preserve the mass and perform the specified preparation separately. Sifting cannot replace accurate measurement or guarantee that every cake will be fluffier.
Sources
For further detail and to check the information: