Sifting is a way to lighten flour that's gotten packed down in a bag during storage and shipping. It's also useful for mixing dry ingredients together and making sure there aren't any stubborn clumps. You don't need a fancy sifter (though they're great fun!), but a few basic kitchen tools you probably already have.
The simplest way we know to sift flour is to dump it into a strainer over our mixing bowl. A fine-meshed strainer is best, but any old strainer or even a colander can work in a pinch.
Holding the handle with one hand and tapping the strainer gently with the other, the flour will gradually sift through the strainer. If we're sifting other dry ingredients along with the flour, we'll run them through the strainer a few times to make sure everything is evenly mixed.
If you don't have a strainer handy, you can also mix flour with a wire whisk or a fork. You won't get the flour quite as light as when sifting, but this will work to break up any clumps and fluff up the flour a bit.
What's your method for sifting flour?
Related: What's the Difference? Cake Flour, Pastry Flour, All Purpose Flour, and Bread Flour
(Image: Flickr member Southern Foodways Alliance licensed under Creative Commons)
Straw Mat from The ...

I grew up doing it this way. I thought that's what a sifter is...
Even my husband figured out you really need a flour sifter, not a strainer, when he sifted some to help me out on baking day. He chose this one - we love it.
My sister, the dessert queen, says "when did everyone decide that you don't really need a sifter???"
http://www.webstaurantstore.com/stainless-steel-flour-sifter/4071260.html
with a strainer, you can sift faster by stirring your hand through the flour to push it through, instead of just tapping it. you don't need to press on the flour or anything - just move your hand or a spoon through it.
I sift my flour by.. wait for it.. not sifting it. Because I don't own a sifter and also am lazy. I remember I saw somewhere that some pro-baker admitted she never sifts (can't remember who it was or where I saw it.. but I did), and if she doesn't have to, then neither do I!
If I start finding my baking too dense or flour-y, that's when I'll start sifting.
I don't even sift icing sugar or cocoa.. which I admit I SHOULD do with those since they're always clumping. But again, lazy. I just mash out the clumps as I mix.
I'm with bkk ... aside from the kinds with the rotating disks and the squeezey handles (which accomplish the same thing as a mesh strainer or colander) how else would one do it?
I feel like this is a remedial "tip".
I never sift anything. I just kind of tap it out of the measuring cup. If all my baked goods are lumpy or flat, I haven't noticed. I also never bother mixing baking soda/powder and salt with the flour as most recipes suggest - those things can go in with the flour just fine. Hasn't ruined a recipe yet.
Uh, isn't this "sifting"? I was expecting something like the whisk trick, where you use a whisk to fluff things after you measure them into your mixing bowl.
I sift because my flour often has impurities, and nobody likes to find a glue-y lump.
The link to the fancy sifter, which you say is sold at Macy's, does not work anymore. Can you please help me find it elsewhere?
I happened upon the whisk trick accidentally and now I'm hooked.
Um, the object described is a sieve or yes, a sifter: http://en.wikipedia.org/wiki/Sieve
This is how everyone sifts flour. You're so silly Kitchn.
I pull a "Barefoot Contessa" and basically I fluff the flour in the bag/flour container with my measuring cup before measuring.
I only sift the flour when it's called for... because if the recipe doesn't say sifted flour, then I don't. Because I'm lazy.
Um, I don't think "flour lightening" is actually a baking concept.
The "pro baker" you are thinking of is Rose Levy Bernabaum, the author of the awesome Cake Bible and others. If I recall correctly, she wrote her dissertation on flour sifting. Sifting is important, but only in that the aeration helps the liquid distribute evenly. Sifting can make a small difference in measurements, which is why the best writers always use weight rather than volume to measure dry ingredients.
Yup. This is how one sifts flour.
Why would you want that other gadget? A regular strainer/sifter is much more versatile.