A few quickies ;)

Sifting aerates dry ingredients and sieves out lumps. Sifting helps distribute small amounts of ingredients like salt or baking powder throughout the flours. Sifting also help achieve a specific density and helps one get an accurate measurement. For instance, it is common to see a recipe call for "X cups of sifted flour." I have heard that one reason for sifting flour was that it removed any insects that might be in the flour. That said, I weigh my ingredient, I don't have bugs in my flour, and I seldom sift.

Resting dough allows gluten fibers to relax. If you don't let the dough rest, it is much harder to work. When you roll it, the dough tends to spring back to the original shape and thickness. Letting dough rest also allows time for moisture to redistribute.

Over-working dough generally applies to short doughs like cookies and pie pastry. You don't want to prolong the working time because the more you manipulate the dough, the more the gluten develops. Over-working results in a very dough product. Bread doughs, on the other hand, benefit from thorough working and it is very difficult to over-work them, especially by hand.

That was EXACTLY what I was looking for thank you!

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