Final answer:
Nelson Mandela was imprisoned for 27 years, after which he became South Africa's first Black president and led the nation's transition to a multiracial democracy.
Step-by-step explanation:
Nelson Mandela was imprisoned for 27 years before his release in 1990. After his conviction for sabotage and treason due to his efforts to fight the oppressive apartheid system in South Africa, Mandela became an international symbol of resistance and hope. Following his imprisonment, he was a pivotal figure in the antiapartheid movement and was later elected as the first Black president of South Africa in 1994, leading the country towards a multiracial democracy.