The ruble or rouble (Russian: рубль, romanized: rublʹ; symbol: ₽; ISO code: RUB) is the official currency of the Russian Federation. Banknotes and coins are issued by the Central Bank of Russia, which is Russia's monetary authority independent of all other government bodies.

The ruble is the second-oldest currency in continuous use and the first decimal currency. The ruble was the currency of the Russian Empire, which was replaced by the Soviet ruble (code: SUR, 810) during the Soviet Union. Following the dissolution of the Soviet Union, by 1992, the Soviet ruble was replaced in the Russian Federation by the Russian ruble (code: RUR, 810) at par. The Russian ruble then further continued to be used in 11 post-Soviet states, forming a "ruble zone" until 1993. The ruble was further redenominated with the new ISO 4217 code "RUB, 643" just preceding the 1998 financial crisis, and was exchanged at the rate of 1000 RUR = 1 RUB. Code "RUR, 810" was then excluded from both the ISO 4217 standard and the Russian currency classifier [ru], but continues to be used for numbering bank accounts internally within Russia.

The ruble is a free-floating currency and is subdivided into 100 kopecks which have fallen out of use due to inflation. In 2023, the digital ruble was introduced. The Russian ruble is also used as a de facto legal tender in Baikonur, Abkhazia and South Ossetia.

The ruble has been used in Russian territories since the 14th century, and is the second-oldest currency still in circulation, behind sterling. Historically, the grivna, ruble and denga were used across Russian territories as measurements of weight. As a result of monetary reforms by Peter the Great, the ruble was minted in Russia as a circulating coin in 1704, shortly before the establishment of the Russian Empire. It was also the first currency in Europe to be decimalised in 1704, when it was divided into 100 kopecks. The silver ruble was used until 1897, and the gold ruble was used until 1917.

The Soviet ruble officially replaced the imperial ruble in 1922 and continued to be used until 1993, when it was formally replaced with the Russian ruble in the Russian Federation and by other currencies in other post-Soviet states. The ruble has seen several incarnations and redenominations during its history, the latest of which is the introduction in 1998 of the current Russian ruble (code: RUB) at the rate of 1 RUB = 1,000 RUR.

According to one version, the word "ruble" is derived from the Russian verb рубить (rubit), "to cut, to chop, to hack", as a ruble was considered a cutout piece of a silver grivna. According to Ivan Kondratyev:

Rubles were parts of the grivna or pieces of silver with notches indicating their weight. Each grivna was divided into four parts; the name "ruble" came from the word "cut" because the silver rod weighing 1 grivna was split into four parts, which were called rubles.

Others say the ruble was never part of a grivna but a synonym for it. This is attested in a 13th-century birch bark manuscript from Novgorod, where both ruble and grivna referred to 204 grams (6.6 troy ounces) of silver. The casting of these pieces included some sort of cutting (the exact technology is unknown), hence the name from рубить (rubit). Another version of the word's origin is that it comes from the Russian noun рубец (rubets), the seam that is left around a silver bullions after casting: silver was added to the cast in two steps. Therefore, the word "ruble" means "a cast with a seam". A popular theory deriving the word ruble from rupee is probably not correct.