National Caviar Day takes place on July 18, 2017. Caviar is a product made from salt-cured fish-eggs of the Acipenseridae family. The roe can be "fresh" or pasteurized, with pasteurization reducing its culinary and economic value. Caviar is considered a luxury delicacy and is eaten as a garnish or a spread.
The four main types of caviar are Beluga, Sterlet, Ossetra, and Sevruga. The rarest and costliest is from beluga sturgeon that swim in the Caspian Sea. Cheaper alternatives have been developed from the roe of whitefish and the North Atlantic salmon.
Commercial caviar production historically involved stunning the fish and extracting the ovaries. Another method is extracting the caviar surgically which allows the females to continue producing roe but this method is very painful and stressful for the fish and is illegal in some countries. (With material from: Wikipedia)