Describe the process through which apartheid was dismantled in South Africa. Why was the process relatively nonviolent?

Translated from the Afrikaans word meaning “apartness, or separateness,” apartheid (1948–1994) was a social and political system and ideology supported by the National Party of South Africa, which institutionalized racial segregation and promoted white supremacy and the separate development and freedom of the different racial groups that lived in South Africa (Black African, Colored, and Asian South Africans).
During apartheid, for a white person to know or be friends with a non-white person was very rare and frowned upon, and having an interracial relationship was unheard of. White people were the only ones who got good housing and employment opportunities (grand apartheid) and were the only people allowed to use public facilities such as restaurants, parks, beaches, or swimming pools and attend various social and cultural events (petty apartheid).
One of the main reasons why apartheid was much worse than segregation was the fact that it was made law. Thus, many organizations (such as the African National Congress) and other countries have criticized the apartheid ideology, which prompted the start of some of the greatest social and political movements of the last century and the end of the apartheid system.
There were several violent occasions which showed the brutality and injustice of the apartheid regime, such as the killing of sixty-nine unarmed black protesters by the South African police, in 1963. However, the dismantlement of apartheid was a relatively nonviolent process.
It all started with a series of negotiations between the National Party, the African National Congress, and various political organizations, which lasted from 1990 to 1994. The main subjects of discussion were, of course, the weakening of the white community, the economic struggles of South Africa, and the internal political violence in the country, which, ironically, greatly contributed to the eventual downfall of the apartheid regime.
In 1990, State President F. W. de Klerk delivered a powerful speech about cultural and social equality. He received the support of all black majority leaders and was heavily criticized by the white majority leaders and right-wing opposition parties and extremists, who called him a traitor. In a bold and courageous move, de Klerk lifted the ban on the ANC (African National Congress) and two other black liberation parties, allowed and guaranteed freedom of the press, and, finally, released political prisoners.
Thus, on February 11, 1990, the ANC leader and future South African president Nelson Mandela was released after spending twenty-seven years in prison, which, essentially, marked the beginning of the end of apartheid. After that, Mandela traveled across the country, and even visited the United States, to speak about the importance of peace, freedom, and equality. In April 1994, Nelson Mandela was elected as South Africa's first black president.