Herbs are the aromatic leaves of herbaceous plants (plants with stems that are soft rather than woody). They are valued in the kitchen for their natural aromatic oils, which are used to accent and enhance the flavor of foods or, on occasion, to provide the essential ingredient in a recipe, such as basil in pesto and dill in dill sauce. Herbs are also used as fragrances, medicines, cosmetics, teas, dyes and ornaments.

Spices come from the seeds, bark, roots, fruit or flowers of plants. They add flavor and color to both sweet and savory dishes. Like herbs, they are a component of fragrances and medicines. For thousands of years spices were an important world commodity, actively traded and in part responsible for expeditions that led to the discovery of the New World. During the Middle Ages the demand for spices in Europe was so great that they were considered as valuable as gold.

Fresh herbs for cooking have enjoyed a surge in popularity in recent years. Some of the more common fresh herbs, such as basil, chives, dill, mint, oregano, rosemary, sage, tarragon and thyme, are available year-round in large supermarkets. They can be found either cut or potted. Most herbs are easily grown in the home garden. Dried herbs and spices, both leaf and ground form, are readily available all year in any supermarket.

When purchasing fresh herbs, look for brightly colored, fresh-looking leaves without any brown spots or signs of wilting.

Fresh herbs are very perishable, so purchase them in small amounts. For short-term storage, place the herb stems in water. Cover leaves loosely with a plastic bag or plastic wrap and store in the refrigerator. They will last from two days (basil, chives, dill, mint, oregano) to five days (rosemary, sage, tarragon, thyme).

When purchasing dried herbs or spices, mark each container with the purchase date and discard any remaining after six months. Buy small quantities of infrequently used herbs and spices. Store in a cool, dry place in tightly covered lightproof containers. Do not place above the range as heat and moisture will cause the flavor to deteriorate more quickly.

When herbs are dried, their oils become more pungent. As a general rule when substituting dried herbs for fresh, use 1 teaspoon dried herbs for 1 tablespoon chopped fresh herbs.

There are many herb-and-spice blends available at the supermarket. Most are composed of spices and herbs found in the spice section of grocery stores. Spice blends have the advantage of convenience. Some of the more common blends are: bouquet garni, fines herbes, herbes de Provence,Italian seasoning, poultry seasoning, apple pie spice, celery salt, chili powder, curry powder, five-spice powder, garlic salt, pizza spice, pumpkin pie spice and seasoned salt.