Currently, Beluga caviar is the most premium top notch caviar to buy. It is pale silver-gray in color; and, it is prized for its soft extremely large (pea-size) eggs. Traditionally, the term caviar referred only to roe (fully ripe internal egg masses in the ovaries, or the released external egg masses of fish) from wild sturgeon in the Caspian and Black Sea (Beluga, Osseter and Sevruga caviars).

Today, depending on the country, caviar may also be used to describe the roe of other fish such as salmon, steel head, trout, lump fish, whitefish, carp and other species of sturgeon. And, caviar now comes in a variety of colors, including shades of red, orange, gray, brown and black, based on the species of fish and any additives. For example, Osseter is gray to brown, while trout caviar is orange.

For many centuries and still in the 21st, caviar is considered a delicacy and is eaten as a garnish or a spread. From royal families to everyday people, caviar will remain on the list of notable hors d'oeuvre (appetizers) to serve on special occasions.

More Info: en.wikipedia.org