Short answers, pulled from the story.
The Democratic People's Republic of Korea was formally established on the 10th of July 1948, with Kim Il Sung as premier and Soviet general Terentii Shtykov as the first Soviet ambassador. Soviet forces withdrew from the North later that same year.
Approximately 3 million people died in the Korean War, which began on the 25th of June 1950 when North Korea invaded the South. Kim Il Sung and Soviet ambassador Shtykov lobbied Joseph Stalin to support the invasion as a means to unify the peninsula under socialism. An estimated 12-15% of the North Korean population died in the war, a proportion close to or surpassing the share of Soviet citizens killed in World War II.
North Korea announced it had conducted its first nuclear weapons test on the 9th of October 2006. The program accelerated after the United States rejected the Agreed Framework in 2001, and North Korea was estimated to possess 50 nuclear warheads as of recent assessments, with ballistic missiles capable of reaching up to 15,000 km.
The North Korean famine, which began in the mid-1990s following flooding that damaged crops and infrastructure, resulted in the deaths of an estimated 240,000 to 420,000 people. The share of malnourished children reached 60% in 1998 before international food aid, led by the United States through the World Food Programme from 1997, helped bring that figure down to 28% by 2013.
Juche is the official state ideology of North Korea, first pronounced by Kim Il Sung in a 1955 speech titled On Eliminating Dogmatism and Formalism and Establishing Juche in Ideological Work. Its core tenets are economic self-sufficiency, military self-reliance, and an independent foreign policy. It was written into the constitution in 1972 and by the 1980s had fully replaced Marxism-Leninism.
A 2014 United Nations inquiry found systematic, widespread, and gross human rights violations with no parallel in the contemporary world. An estimated 200,000 prisoners are held in six large political prison camps, and the International Coalition to Stop Crimes Against Humanity in North Korea estimates over 10,000 people die in these camps annually. North Korea has the highest rate of modern slavery in the world, with 10.4% of its population in forced labor according to Walk Free's 2018 Global Slavery Index.