Whilst feeding, the bird wades about, stirs up the mud with its feet, and, reversing the ordinary position of its head so as to hold the crown downwards and to look backwards, sifts the mud through its bill.
The smaller the particulate, the easier it is for such particles to become airborne when a cat sifts around the litter in its box.
JustFreeBooks is a useful search engine that sifts through all of the top public domain online directories and provides you with a full listing of where the book that you're looking for is available online for free.
The child sifts through the sand to find the gold.
So, Yahoo does actually use an algorithm for its web crawler, which sifts through hundreds of thousands of sites on the Internet constantly.