Short answers, pulled from the story.
The Russian Empire was officially established on the 11th of November 1721 when the Governing Senate and Synod invested Tsar Peter I with the title of Imperator of all Russia. This event marked the formal transformation of the Russian state into an empire following the Great Northern War.
Peter the Great founded the Russian Empire by ruling from 1682 to 1725 and seeking a window to the sea through the Great Northern War against Sweden. He aimed to transform Russia into a major European power by building Saint Petersburg and reorganizing the government and church under his authority.
Catherine the Great reigned from 1762 to 1796 and implemented reforms that included abolishing state service for nobles and granting them control of most state functions in the provinces. She also extended Russian political control over the lands of the Polish Lithuanian Commonwealth and waged war against the Ottoman Empire to gain territory near the Black Sea.
The Russian Empire ended with the proclamation of the Russian Republic on the 1st of September 1917 following the October Revolution by the Bolsheviks. The collapse was caused by political dysfunction, continued involvement in World War I, and widespread food shortages that led to mass demonstrations and the execution of the Romanov family in July 1918.
At its greatest extent in the late 19th century the Russian Empire covered a surface area of 22,800,000 km2 and ranked as the third largest empire in world history. It spanned most of northern Eurasia from the Arctic Ocean to the Black Sea and from the Baltic Sea to Alaska.
The Emancipation Reform of 1861 freed the serfs and is considered the single most important event in 19th century Russian history. It marked the beginning of the end of the landed aristocracy's monopoly on power and provided a supply of free labor to the cities to stimulate industry.