Nut butter is a dense paste made by crushing nuts. The paste is designed to be spreadable, and it can be used in a wide assortment of ways to make everything from sandwiches to savory sauces. One of the most famous types of nut butter is probably peanut butter; oddly enough, peanut butter isn't technically a nut butter, because peanuts are legumes, not nuts. However, peanut butter is considered a member of the nut butter family because the nutritional composition of peanuts is similar to that of true tree nuts.

In addition to being made from tree nuts like almonds, walnuts, cashews, hazelnuts, macadamia nuts, pecans, and pistachios, nut butter can also be made from oil-rich seeds like sunflower seeds, sesame seeds, and pumpkin seeds. Each type of nut butter has a distinct flavor and nutritional profile; most tend to be high in fats and protein, with a very rich, creamy flavor.

The nuts used in nut butter may be roasted or raw. Roasted nuts tend to create a nut butter with a richer, more intense flavor, while raw nuts result in a milder nut butter. When the nuts are very finely ground, the result is sometimes referred to as a creamy nut butter, in contrast with a chunky nut butter, in which chunks of whole nuts are allowed to remain intact. Creamy nut butter is much more spreadable, with an even texture which is akin to that of the butter made from cow's milk.

Most markets carry peanut butter at a minimum, and sometimes an assortment of other nut butters are available as well. Stores with their own nut grinders may allow customers to grind nut butter on demand, ensuring a fresher flavor. It is also possible to make nut butter at home; nuts can simply be crushed and then ground in a blender or food processor with a small amount of oil for lubrication.

Because nuts are high in fats, nut butters can go rancid easily. If you have freshly ground nut butter, you should keep it refrigerated, and you should also try to use it within a few months. Sealed nut butter like that found in the store can be kept at room temperature as long as it is sealed, but as soon as it is opened, you should refrigerate it to ensure that the oils do not go bad.

Nut butter also has a tendency to separate, with the oil rising to the top and the meat of the nuts sinking to the bottom. If nut butter has separated, you can either open the container and gently agitate the contents with a long knife or spoon, or you can invert the container for a few hours to encourage the oil to percolate through the meat of the nut butter.

While nut butter is classically used as a sandwich spread, the imagination is the limit when using nut butters. They can also be spread on crackers or fresh fruit, made into rich sauces such as Thai peanut sauce, or eaten straight. Some people find nut butter to be an excellent snack if they start flagging during the day, since it provides a quick hit of protein.