They are small spaces where you can keep things. All of the little drawers in a piece of furniture could be called nooks and crannies. In the article about Muffins, that phrase "nooks and crannies" is used by the Thomas English Muffin company to describe how there muffins have little "holes" that catch the melted butter. A lot of people like that. The article comes with a perfect picture: http://www.nydailynews.com/money/2010/06/15/2010-06-15_recipe_for_a_lawsuit_as_muffin_guy_tied_to_rival.html Also nooks and crannies could be all of the small spaces on a cliff/ mountain. Sometimes birds lay their eggs in all the nooks and crannies on the cliff next to the ocean because they are protected from predators.

it means "everywhere" I've tried looking for my earring in every nook and cranny but I still can't find it :(

角落和缝隙