This national holiday is always celebrated on 12 June. If Russia Day falls on a weekend, then an additional holiday on a weekday is usually declared.
The National Day of the Russian Federation, Russia Day commemorates the formal adoption, on 12 June 1991 of the Declaration of Sovereignty of the Russian Federation which declared Russia's "independence" from the USSR.
Since 1991, the holiday has changed its name twice. It was originally called 'Independence Day'.
In 1994 it was renamed to the catchy 'Day of the adoption of the Declaration of Sovereignty of the Russian Federation'.
On 1 February 2002 it was officially renamed to Russia Day.
In accordance with this name, this holiday is generally celebrated as a show of patriotism for Russia.
It's celebrated in a similar way to Victory Day, with holiday events culminating in an evening fireworks display.
While it has been an official holiday since since 1991, 2003 was really the first year that it was celebrated in a major way, when it was promoted by Vladimir Putin.