Originally, the point of sifting flour used to be to remove lumps and the occasional insect, although modern flour is generally free of those concerns. If you don't buy pre-sifted flour, sifting can still be a good idea for a number of reasons.

First, it loosens up flour that has been sitting around in storage for a long time, aerating it and helping your baked goods to have a lighter texture. It's also a good idea to sift flour if you are combining it with other ingredients, such as salt, baking powder or soda, or cocoa powder, to give the mixture a homogeneous texture.

Flour can be sifted either with an old-fashioned sifter, or by shaking flour through a sieve. Dry ingredients can also be whisked together with a wire whisk in a pinch, which also helps lighten up the flour. 

Nevertheless, some people think that sifting flour is a pain, and skip it altogether, claiming they don't notice the difference. Do you?

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