Short answers, pulled from the story.
The Russian ruble (symbol: ₽; ISO code: RUB) is the official currency of Russia, issued by the Central Bank of Russia. It is also used as de facto legal tender in Baikonur, Abkhazia and South Ossetia.
The Russian ruble has been used in Russian territories since the 14th century, making it the second-oldest currency still in continuous circulation, behind only the British pound sterling. Its first chronicle mention as an accounting unit is recorded under the year 1316.
The word ruble is most commonly traced to the Russian verb rubit, meaning "to cut" or "to chop," because early rubles were considered cutout pieces of a silver grivna rod. An alternative theory derives the name from rubets, the Russian word for the seam left on a silver casting after a two-step pour.
In 1704, Peter the Great reformed the Russian monetary system and divided the ruble into 100 copper kopecks rather than the older denomination of 200 Moscow denga coins. This made Russia the first country in Europe, and the first in the world, to adopt a decimal currency system.
The ruble was redenominated in 1998 at a rate of 1,000 old rubles (RUR) to one new ruble (RUB), just before the financial crisis struck. In the six months following the crisis, the ruble lost 70% of its value against the U.S. dollar. It stabilized at around 30 rubles per dollar from 2001 to 2013 before depreciating again.
The official ruble symbol, a Cyrillic letter Er with a single horizontal stroke, was adopted on the 11th of December 2013. It was accepted into Unicode 7.0 on the 16th of June 2014, following approval by the Unicode Technical Committee at its 138th meeting in San Jose on the 4th of February 2014.
The digital ruble is a central bank digital currency issued by the Bank of Russia, convertible to cash and non-cash at a 1:1 rate. It was officially launched on the 15th of August 2023, after the President of Russia signed the enabling law on the 24th of July 2023.