How Do Potato Chips Stay Fresh In The Bag?

How Do Potato Chips Stay Fresh In The Bag?

            http://indianapublicmedia.org/amomentofscience/potato-chips-stay-fresh-bag/

            http://www.eatbydate.com/other/snacks/potato-chips-shelf-life-expiration-date/

            http://wiki.answers.com/Q/Which_gas_is_put_into_bags_of_crips_to_keep_them_fresh#slide=1&article=Which_gas_is_put_into_bags_of_crips_to_keep_them_fresh

            http://www.livestrong.com/article/473752-how-to-crisp-stale-crackers-chips/

            http://www.wikihow.com/Close-a-Bag-of-Chips-by-Folding-It


Of course one can just eat them quickly, like within a day or so.