These are the ideas that, for better and worse, helped make 2005 what it was. You’ll find entries that address momentous developments in Iraq (“The Totally Religious, Absolutely Democratic Constitution”) as well as less conspicuous, more ghoulish occurrences in Pittsburgh (“Zombie Dogs”). There are ideas that may inspire (“The Laptop That Will Save the World”), that may turn your stomach (“In Vitro Meat”), that may arouse partisan passions (“Republican Elitism”) and that may solve age-old mysteries (“Why Popcorn Doesn’t Pop”). Some mysteries, of course, still remain. For instance, we do not yet have an entirely satisfying explanation for how Mark Cuban, the outspoken Internet mogul and N.B.A. owner, came to be connected with three of the year’s most notable ideas (“Collapsing the Distribution Window,” “Scientific Free-Throw Distraction” and “Splogs”). That was just one surprising discovery we made in the course of assembling the issue. In the pages that follow, we’re sure you’ll make your own. Go to the Issue