Herbs have been used in a variety of applications over the course of human history, for cooking, healing, aroma therapy, and much more. Herbs are plants whose uses are informed by their unique and individual properties. They are sold at myriad retail establishments and more exotic varieties can be purchased at specialty stores and online. Herbs are sold both fresh and dried. Most botanists and other experts would likely classify herbs into one of two categories: those used for culinary purposes and those used for medicinal reasons. Culinary herbs are most commonly the leafy part of the plant. Culinary herbs are different than spices in that the latter are typically derived from other portions of the plant, including berries, seeds, roots, and fruit. Many herbs that would be classified as medicinal are also derived from various other parts of the plants than just the leaves. There are perennial, biennial, and annual culinary herbs. Lavender and thyme are two examples of perennials, parsley is a commonly known biennial herb, and basil is perhaps the most widely used annual herb. It is possible for some perennial herbs to come from shrubs, as in the case of Rosemary. Herbs are generally used in relatively small amounts to lend flavor to a culinary dish, while spices could be said to more directly affect the consistency of the dish. Many retail grocery stores and other such markets sell both dried and fresh herbs. Grocery stores sell a large selection of dried herbs as well as fresh ones like basil, green onion, and parsley, to name just a few.