A denga was a Russian monetary unit with a value latterly equal to ½ kopek (100 kopeks = 1 Russian ruble).
Production of dengas as minted coins began in the middle of the 14th century. In their earliest form they were imitations of the silver coinage of the khans of the Golden Horde, usually bearing blundered or meaningless legends. Weighing about a gram, they were prepared by cutting silver wire into measured lengths, beating each length flat, and then striking the resulting blank between two dies. This resulted in slightly elongated coins, often showing traces of the original wire from which they had been taken. From Dmitry Donskoy's time onwards the coins began to take a more Russian form, with depictions of people, animals and Russian legends, although legends partly in Arabic (the official language of the Horde) persisted on some coins until the time of Ivan III.
Dengas were made only in the southern Russian principalities; the state of Novgorod and the City of Pskov made their own slightly larger coins. In 1535 a reform took place, with the northern "novgorodka" being valued at twice the southern denga or "moskovka". In the 1540s novgorodkas depicting a horseman with a spear (Russian kop'e) began to be made, and novgorodkas were thenceforth known as kopeks.
The minting of silver dengas seems to have decreased after the 16th century, as they are found less often in hoards, but they are known until the reign of Peter the Great. By that time the coinage had devalued so far that dengas weighed only about 0.14 grams, and were of little practical use. In the coinage reform of 1700 they reappeared as much larger copper coins, and mintage continued, off and on, until 1916, just before the Romanov dynasty ended in 1917.
Coins minted in the 18th century invariably showed the denomination as Denga, but during parts of the 19th century this was replaced by the word Denezhka, the diminutive form of Denga. Later still the denomination was shown simply as ½ Kopek.
The plural form of Denga, den'gi (деньги) has become the usual Russian word for 'money'.