Actually, it is fish eggs, but as an interesting quote says in ZwyerCaviar:
"Caviar definitely is not food. It's a unique product representing many things - an experience, a handiwork, a specialty, a dream perhaps"
Caviar is the processed, salted roe of certain species of fish, most notably the sturgeon (black caviar) and the salmon (red caviar). It is commercially marketed worldwide as a delicacy and is eaten as a garnish or a spread; for example, with hors d'oeuvres.
Caviar is processed, salted, non-fertilized roe marketed as a luxury food. According to the Food and Agriculture Organization, caviar is a product made from salt-cured fish-eggs of the Acipenseridae family. The roe can be "fresh" (non-pasteurized) or pasteurized, with pasteurization reducing its culinary and economic value.
Traditionally the term caviar refers only to roe from wild sturgeon in the Caspian and Black Seas (Beluga, Ossetra and Sevruga caviars). Depending on the country, caviar may also be used to describe the roe of other fish such as salmon, steelhead, trout, lumpfish, whitefish, and other species of sturgeon.