Nuts today are almost all commercially grown, unlike the early days in the United States when families gathered nuts in forests. Nuts are the dry fruit of trees. The outside covering of most nuts is the shell, the inside edible part is called the "meat." Some foods we call nuts are actually seeds, but they are included here. For example, peanuts are seeds of a legume and Brazil nuts are seeds of a South American tree.

There are many kinds of nuts available in a variety of forms. Following is a description of the most common types of nuts sold in the United States:

Almonds are oval, flat white nuts with thin brown skin and light tan pitted shells. There are two types of almonds, bitter and sweet. The bitter variety contains toxic prussic acid when raw. The acid is destroyed by heating, so commercial processors use this stronger flavored almond to make extract and liqueurs. Sweet almonds have a delicate, slightly sweet flavor and are used for baking and cooking.

Cashews are the seeds of a tropical fruit called a cashew apple. The nut grows on the outside of the fruit at its base. This nut has a kidney-shaped shell which is highly toxic. The shell is removed commercially, and the nut is cleaned before marketing. The nut itself is kidney-shaped with a sweet, buttery flavor and crunchy texture. Cashews are 48 percent fat. They are generally used for snacking and cooking, especially in Chinese stir-fries.

Macadamia nuts are native to Australia, but most of the commercial crop is now grown in Hawaii. This small, round nut has a hard brown shell with cream colored meat and a buttery rich, slightly sweet flavor. Most are sold shelled, either roasted or raw. They are used for snacking and baking.

Peanuts are grown throughout the southern part of the United States and have a soft, thin netted tan-colored shell. The nuts have a reddish-brown papery skin, ivory-colored flesh and a buttery, nutty flavor that is intensified by roasting. They are used for snacking, baking and for peanut butter.

Pecans are native to the United States and a member of the hickory family. They are widely grown in Georgia, Oklahoma and Texas. The nut has a smooth tan shell which is thin, but hard. The flesh is beige with a thin brown exterior. These nuts are widely eaten out of hand and used in a variety of sweet and savory dishes.

Pine nuts are found inside pine cones. The cones are generally heated to extract the nuts. This labor-intensive process makes these nuts expensive. They have a long, narrow ivory-colored "meat" and a faint pine flavor. They are used in Mediterranean cooking and are an important ingredient in pesto.

Pistachio nuts have a hard tan shell which is sometimes dyed pink or blanched until white. They are grown in California, Iran, Italy and Turkey. The inside meat has a pale green color and a delicate, subtly sweet flavor. Generally eaten as an out-of-hand snack, pistachios may also be used in baking and cooking.

Walnuts are encased in a hard, light brown shell. The two most popular varieties are the English and the black walnut. The English variety is most common and has a milder flavor. Black walnuts have a strong, rich flavor. The black walnut shell is extremely difficult to crack and can stain your skin.

Shelled nuts are available all year and are sold in bulk, vacuum-packed in cans and jars, or in cellophane bags. Depending on the specific type of nut, they may be sold oil- or dry-roasted and salted or unsalted. They are sometimes sweetened with sugar or honey, seasoned with spices or covered with chocolate. Unshelled nuts are available in bulk especially during November and December.

When purchasing nuts in their shell, look for clean, unbroken shells without cracks or splits. Nuts should feel heavy for their size and appear well shaped. Shelled nuts should be plump, crisp and uniform in size and color.

1 pound unshelled nuts = 3 to 4 cups chopped.

Store unshelled nuts in a cool, dry and dark place. Heat, light and moisture encourage rancidity. They can be kept for several months. Shelled nuts will keep in an airtight container up to 4 months refrigerated and 6 months if frozen.

Toasting gives nuts a rich, fuller flavor. To toast nuts spread them in single layer on a baking sheet and toast them in a preheated 350°F oven for 8 to 10 minutes. Watch carefully and stir them once or twice for even browning. An alternative method is to stir the nuts in a heavy skillet over low heat for 3 to 4 minutes until brown. Always cool nuts before adding them to other ingredients.

To reduce the risk of overprocessing when grinding nuts in a food processor, add a small amount of the flour or sugar from the recipe. If they are overprocessed, nuts will become nut butter.