"It has layers" would be a great tag line for a new line of frozen baclava. But now it's the zombie chant of idiot internet detectives who believe they found proof that Obama's birth certificate is fake while goofing around on the computer at work. This shit's never gonna end.
See, when you open up Obama's birth certificate in image-editing software, you can see and manipulate "layers" of different elements of text. Obviously, some White House intern spent the last two weeks painstakingly photoshopping the document, right? Drudge linked to a video about it and everything!
This conspiracy theory—that the White House would engage in a massive coverup only to leave the most obvious tracks of forgery—is so dumb that we will let a YouTube commenter on the video above debunk it:
It's called OCR (optical character recognition). Acrobat and many scanners do this by default. It detects letters and words on the page and allows you to add selectable text to the document without having to type it in manually.
Notice how when you hide a layer, it's white behind it? If it was truly forged, you wouldn't see any of the background missing. It's white because it doesn't know what's behind the text BECAUSE THE TEXT WAS THERE WHEN IT WAS SCANNED.