What is '6 row' malt?

[shifty]

"I have tasted Jack Daniels that was homemade that was better than the original, using the JD mashbill. The distillery uses 80% corn, 12% rye, 8% malt (6-row). They ferment with 25% backset from a previous distillation run- homemakers should do the same. They use a 64inch diameter copper beer still with a doubler- but a homemade potstill with two runs (collect one-third of the mash volume out of the still as low wines, then re-run it, collecting from 75%abv to 55%) works just as well. The resulting spirit is then aged on charred American oak, and sweetened with a dash of REAL maple syrup (the kind that has a slight smokey flavor)- this will taste JUST like the store bought spirit- but will be a LOT smoother. The spirit should be aged at less than 65%abv, to prevent vanillins from clouding up the smokey sweetness from the maple syrup."

I wanted to have a crack at this but i was just wondering what the difference is between 6 row and normal malt?
Cheers all....