Short answers, pulled from the story.
The House of Romanov began ruling Russia on the 21st of February 1613, when the Zemsky Sobor elected sixteen-year-old Michael Romanov as tsar. This made the Romanovs Russia's second reigning dynasty, succeeding the Rurik dynasty that had ended with the childless death of Feodor I in 1598.
The Romanovs gained prominence when Anastasia Zakharyina, a descendant of the medieval boyar Andrei Kobyla, married Ivan IV (the Terrible) on the 3rd of February 1547, making her the first tsaritsa of Russia. The family name Romanov itself derived from Roman Yurievich Zakharyin-Yuriev, whose grandchildren adopted it during Ivan's reign.
Nicholas II, his wife Alexandra, their five children, and four servants were executed in the cellar of the Ipatiev House in Yekaterinburg on the night of 16-the 18th of July 1918, by Bolshevik revolutionaries most likely acting on orders from Vladimir Lenin. Those who survived the initial gunfire were stabbed or struck with rifle butts; diamonds sewn into the children's clothing had partially deflected the bullets.
Dr. Alexander Avdonin discovered the mass grave containing the remains near Old Koptyaki road in Yekaterinburg in the mid-1970s, but concealed the find until the fall of the Soviet Union. The grave was officially excavated in 1991, and identities were confirmed using DNA analysis including a sample from Prince Philip, Duke of Edinburgh. The remains were interred at Saints Peter and Paul Cathedral in St. Petersburg in 1998.
When Empress Elizabeth died childless in 1762, the direct male Romanov line ended, and the throne passed to her nephew Peter III, who was an agnatic member of the German House of Holstein-Gottorp. His descendants adopted the Romanov surname through their matrilineal descent from Peter the Great, and the 1944 edition of the Almanach de Gotha records the dynasty's name from Peter III onward as Holstein-Gottorp-Romanov.
Of the House of Romanov's 65 members, 47 survived and went into exile abroad after the February Revolution of 1917. In 1924, Grand Duke Kirill Vladimirovich, the senior surviving male-line descendant of Alexander II, claimed the headship of the defunct Imperial House of Russia.