Caviar is the processed salted roe of various species of fish, most notably sturgeon. It is commercially marketed throughout the world as a delicacy and is eaten principally as a garnish or spread, as with hors d'œuvres. The name "caviar" comes from the Persian word Khāg-āvar, which means "the roe-generator". This name in Persian means the sturgeon and its product, the roe. Russian uses an unrelated name, икра ikra which simply means "roe".

Today, black caviar comes from sturgeon that is fished from the Caspian Sea by Azerbaijan, Iran, and Russia. Some of the highest prices are paid for Beluga, Ossetra, and Sevruga varieties (note that the large-grained Beluga caviar comes from the Beluga sturgeon and has nothing to do with the Beluga whale — whales do not lay eggs). The rare golden Sterlet caviar was once the favorite of czars, shahs and emperors, but the species is now nearly extinct. Dwindling yields due to overfishing and pollution have resulted in less costly alternatives, processed from the roe of whitefish and North Atlantic salmon, becoming popular. The word "malossol" on the label means "little salt" in Russian, and indicates that it has been processed with a minimum amount of salt. Caviar contains typically 4–8% salt, with the better varieties generally containing less salt.

In the early 1900s, both Canada and the United States were major suppliers of caviar to Europe, harvesting the eggs from lake sturgeon in the midwest, and from Shortnose sturgeon and Atlantic sturgeon that spawned in East Coast rivers. However, today the Shortnose sturgeon is listed as Vulnerable in the IUCN Red List of endangered species and as Endangered under the U.S. Endangered Species Act.

In recent years, the aquaculture of sturgeon has been increasing, especially in France, Uruguay and California. In recent years, paddlefish and hackleback caviar have increased in popularity. These lower-priced caviars are also from the sturgeon family. Recently, the amount of allowed wild harvesting is being reduced, driving the price upward.

The United States Fish and Wildlife Service banned the import of Beluga caviar from the Caspian Sea in September 2005 in an attempt to protect the endangered Beluga sturgeon. A month later, it extended the ban to Beluga caviar from the Black Sea basin for similar reasons.

In January 2006, CITES, the convention for trade in endangered species, announced that they were "unable to approve the export quotas" for 2006 for caviar from wild stocks. If this is not resolved, the trade in caviar would be limited to that produced in sturgeon farms.

Due to its high price, it is synonymous in Western culture with luxury and wealth in the same way that personal jets, yachts, and mansions are commonly regarded. In Russia and other cultures, though an

expensive delicacy, it is a common part of celebrations such as wedding and holiday feasts.

Typical Swedish sandwich with hard-boiled eggs and cod roe caviar from a tubeServing is done with either horn, wood, or gold utensils (mother-of-pearl and plastic are also common), rather than silver or steel (even stainless), which may alter the taste and color of the caviar.

Commercial caviar production normally involves stunning the fish (usually with a club to the head) and extracting the ovaries, although a number of farmers are experimenting with surgical removal of the roe from live sturgeon, allowing the females to produce more eggs during their lifespans.

Caviar is not generally regarded as part of a vegetarian diet, even by vegetarians who consume milk and eggs. The usual reasoning is that harvesting the eggs involves killing (or performing surgery) upon the fish and thus contributes to animal suffering. Soy-based immitation caviar is produced and sold as an alternative in the vegetarian food market. Caviar is also generally avoided by Jews because the Sturgeon lacks scales and is thus not kosher. However, this is not true for all fish species that the roe is obtained from.

In Scandinavia, a significantly cheaper version of caviar, made from smoked cod roe, can be bought in tubes, suitable for use as sandwich filling. Caviar from burbot, vendace, and whitefish can be bought in Finland in its natural form as an alternative to sturgeon caviar. Caviar from burbot is regarded by some gourmets as such a delicacy that it even outranks Beluga in taste with the fraction of the price of sturgeon caviar.