Short answers, pulled from the story.
Approximately 12 million people were abducted from nearly twenty European countries to serve as forced labourers under Nazi Germany. Counting deaths and turnover over the course of the war, about 15 million men and women were forced labourers at some point. At the programme's peak, forced workers made up 20 percent of the entire German work force.
About two thirds of the roughly 12 million abducted workers came from Central Europe and Eastern Europe. The harshest policies were applied to people from Belarus, Ukraine, and Russia. By January 1944, workers from the occupied USSR numbered approximately 2.165 million, and workers from Poland numbered about 1.4 million, making these the two largest national groups among foreign civilian forced labourers.
More than 2,000 German companies profited from slave labour during the Nazi era. Named firms include Thyssen, Krupp, IG Farben, Bosch, Daimler-Benz, Demag, Henschel, Junkers, Messerschmitt, Siemens, Volkswagen, and Deutsche Bank. The German subsidiaries of foreign corporations, including Fordwerke (Ford Motor Company) and Adam Opel AG (General Motors), also used forced labour.
The German Forced Labour Compensation Programme was established in 2000. A forced labour fund paid out more than 4.37 billion euros to close to 1.7 million then-living victims worldwide, in one-off payments of between 2,500 and 7,500 euros. As of August 1999, 2.3 million survivors were still alive; many received nothing before the fund was created, as German Chancellor Angela Merkel acknowledged in 2007.
Under the Potsdam Agreements of 1945, Poland was directed to receive reparations from the Soviet Union's share rather than from Germany directly. Soviet pressure on the Polish Communist government produced a repayment arrangement that left most Polish victims with little compensation. In 1953, under further Soviet pressure, the People's Republic of Poland formally renounced its right to further reparations claims from the successor states of Nazi Germany.
Ostarbeiter, meaning Eastern workers, were Soviet and Polish civilians mostly rounded up in Distrikt Galizien and Reichskommissariat Ukraine. They were required to wear a badge marked 'OST,' lived under guard in camps surrounded by barbed wire, and were especially vulnerable to the Gestapo and industrial plant guards. Estimates place the total number of Ostarbeiter between three and 5.5 million people.