The Atlantic's fact-checkers, like those at many American magazines, verify every fact to be published in an article. We go word by word, line by line, trying to make sure that every piece of the puzzle is appropriate and that every fact is correct. We retrace the authors' steps, read the books and reports they read (and often those they didn't get to read), talk to the people they talked to, watch the movies they mention, test the recipes they used, and pull in any necessary source that can help confirm everything from the most basic detail to the most comprehensive argument. We try to be fair judges of the article and decide whether it is balanced and comprehensive.

With apologies to Isaiah Berlin, the job calls for being both hedgehog and fox. For instance: Not long ago, in the space of half an hour, I had three checking conversations that ran the gamut from Wilt Chamberlain's teenage sex life (he claimed to have had sex with some 20,000 women in his life, an average of 1.2 women a day, every day since he was 15) to the number of illegal immigrants entering the European Union through Spain (31,200 would-be immigrants were intercepted in 2006, almost double the total of the previous year) to the difference between a valve and a siphon toilet (valves are essentially large plugs, which force water into the toilet bowl when pulled; used in Britain, siphons suck water through a U-bend before it enters the bowl, which avoid leaks and saves water). It's like taking weekly crash courses in a number of subjects.

Through this feature, we hope to open a window on the wonderful, often secret world of the checking department at The Atlantic, made up of a group of curious, tenacious, diplomatic, and diligent editors all dedicated to the rather old-fashioned goal of trying to get it right, no matter what the deadline.