Short answers, pulled from the story.
Adolf Hitler committed suicide on the 30th of April during the Battle of Berlin. His successor, Reichspräsident Karl Dönitz, authorized Germany's surrender through the Flensburg Government.
The first act of military surrender occurred at 02:41 on the 7th of May at the Supreme Headquarters of Allied Expeditionary Forces in Reims. A slightly modified document became the definitive German Instrument of Surrender when signed in Karlshorst, Berlin at 22:43 local time on the 8th of May 1945.
Hostilities were required to cease by 23:01 Central European Summer Time on the 8th of May 1945. That deadline corresponded with 00:01 on the 9th of May in Moscow Time due to the time zone difference.
Crowds massed in Trafalgar Square and up the Mall to Buckingham Palace where King George VI and Queen Elizabeth appeared on the palace balcony alongside Prime Minister Winston Churchill. Churchill moved from the palace to Whitehall to address another large crowd there before conducting the people in singing For He's a Jolly Good Fellow.
The Baltic states Estonia, Latvia and Lithuania officially commemorate the 8th of May instead of the 9th of May since it marked the Soviet occupation in 1944 for these specific countries. The Czech Republic has officially recognized the 8th of May as Victory Day since the Dissolution of Czechoslovakia in 1993.