Wisegeek describes dates thus:
"A date fruit is the product of a date palm, a tree native to Northern Africa and the Middle East, although it is also cultivated in other parts of the world. In addition to being eaten fresh, the date fruit is dried and eaten whole as a snack or included in an assortment of desserts. Many regional Middle Eastern cuisines incorporate dates, as do Mediterranean cuisines like those of Italy and Greece. Dried dates are usually readily available in most markets, and fresh dates can be found in specialty markets in season.
" ... When selecting dates, look for plump, evenly colored specimens. All dates have a single long seed, but they can range in shape from oblong to round, depending on the cultivar. The date should not look dry or withered, and no crystals should appear on the exterior of the date. Fresh dates will last for up to two weeks under refrigeration, while preserved dates can last much longer, depending on how they are preserved."