Graham crackers are a type of lightly sweetened, whole grain cracker that are often used in baking and dessert recipes. The whole crackers can be found sandwiching toasted marshmallows and chocolate in s’mores and the cracker crumbs are a popular choice for the crusts of pies and cheesecakes. The crackers were originally made with graham flour, a whole wheat flour that includes the germ and bran of the wheat, but these days they are more likely to be made with regular unbleached flour or regular whole wheat flour so that they have a lighter texture than the original recipe.
They were invented in the early 1800s by Presbyterian minister Reverend Sylvester Graham. He felt that eating bland foods was a way to train yourself to resist evil and temptation in your life and came up with graham crackers, which were recommended as part of the healthful (and holy) Graham Diet. The cookies outlasted Graham and are still a popular food today, probably because they are sweeter and tastier than the original recipe that Graham conceived, though they are still a relatively plain food.
Graham crackers are available at most stores in the US, but are more difficult to find abroad if you want to make a recipe that calls for them. Fortunately, there are similar plain, wholemeal biscuits that you can substitute for them in a recipe. You can also try your hand at making your own Homemade Graham Crackers, which are easy to make and much more delicious than their store-bought counterparts (you may have difficulty turning them into a crust because you’ll want to snack on them!).