The Holocaust refers to the systematic genocide of various groups by Nazi Germany during World War 2, primarily targeting Jews. An estimated 12 to 26 million people were killed, including around 6 million Jews. Other groups persecuted included Roma (gypsies), Slavs, homosexuals, Jehovah's Witnesses and people with disabilities. Nazi Germany viewed these groups as "undesirable" and imposed racist laws and policies that led to their imprisonment and murder.