A peanut-butter and jelly (or jam) sandwich, or PB&J, includes one or more layers of peanut butter and one or more layers of jelly or jam on bread. Jelly is a fruit based spread, made primarily from fruit juice, while jam contains crushed fruit and fruit pulp. Sometimes the sandwich is eaten open-faced, or with one slice of bread folded over (effectively a "half sandwich"). The sandwich is quite common and popular in North America, especially for children; a 2002 survey showed the average American will have eaten 1,500 of these sandwiches before graduating from high school. Smuckers and other companies manufacture commercial sealed crustless sandwichs made of peanut butter and jelly. There are many variations on the sandwich; for example, honey or sliced fruit can be substituted for the jelly component, e.g. a peanut-butter and banana sandwich. Marshmallow fluff can also be substituted for the jelly, or added for extra flavor; this sandwich is called a "Fluffernutter". The popularity of almond butter has inspired some to transition to "almond butter and jelly" sandwiches; other nut butters are less common. Cream cheese, substituted for the peanut butter, makes a "Cream cheese and jelly" (CC&J) sandwich. Nutella is another possible substitute for one of the spreads. A common problem with the sandwich is that the jelly or jam can make one slice of bread soggy owing to the high water content inherent to the ingredient. This is especially the case when the sandwich is prepared ahead of time as part of a bag lunch. One solution is to create a barrier that protects the bread by taking advantage of the hydrophobic properties of oil present in the peanut butter, often in an emulsified solution. By spreading peanut butter on each slice, the jelly or jam is contained and isolated in the center, and the sandwich can safely be made ahead of time.