On Tuesday, former US President Barack Obama delivered the Nelson Mandela Annual Lecture.
Mr Obama addressed thousands of people including Bill Gates and South African leaders in Johannesburg, South Africa.
He described late Mandela as an inspiration to young people in the late 70s.
"Madiba's light shone so brightly that in the late seventies he could inspire a young college student on the other side of the world to re-examine my own priorities - to reconsider the small role that I might play in bending the arc towards justice," remarked Mr Obama.
"And now an entire generation has now grown up in a world that by most measures has gotten steadily freer, healthier, wealthier, less violent and more tolerant during the course of their lifetimes. It should make us hopeful."
In his speech, Mr Obama tracked the enormous social and democratic progress the world has recorded in the 100 years between Mandela's 1918 birth and 2018.
July 18 marked the 100th birthday of the late Nelson Mandela and individuals and organisations across the globe have reminisced on the impact of the anti-apartheid revolutionary.
Bill Gates wrote, on his official Twitter handle, about Mandela's resilience and consistency in fighting for equality and justice.
"Nelson Mandela was tireless in his pursuit of equality and justice for all. As we celebrate #Mandela100, let's resolve to do everything we can to create the world he dreamed of."
"His relentless commitment to advancing equality and justice was deeply inspiring--and so was the warmth and compassion he brought to his work," Melinda Gates tweeted, adding to Bill's comments.
"We owe our children, the most vulnerable citizens in our society, a life free of violence and fear." Nelson Mandela.
On #MandelaDay, we honour @NelsonMandela's life and work that continues to inspire our world.#Mandela100 pic.twitter.com/tnEctTj0WA
- UNICEF (@UNICEF) July 18, 2018
Also, Nana Akufo-Addo @NAkufoAddo, Ghana President, stated that Madiba as Mandela was "called, lived an exemplary life by demonstrating devotion and dedication".
"Nelson Mandela gave us an example of sacrifice, of dedication to principle, and of devotion to freedom that is without equal in the annals of Africa's modern history," he tweeted.
Mandela Day is about taking action to change the world for the better. In these young people, I see Madiba's example of persistence and hope. They are poised to make this world more peaceful, more prosperous, and more just. pic.twitter.com/GJDuOs1hkH
- Barack Obama (@BarackObama) July 18, 2018
The United Nations International Children's Emergency Fund (UNICEF) also tweeted: "We owe our children, the most vulnerable citizens in our society, a life free of violence and fear." Nelson Mandela. On #MandelaDay, we honour @NelsonMandela's life and work that continues to inspire our world."
Nelson Mandela was tireless in his pursuit of equality and justice for all. As we celebrate #Mandela100, let's resolve to do everything we can to create the world he dreamed of. #MandelaDay pic.twitter.com/HUDuRrgX7R
- Bill Gates (@BillGates) July 18, 2018
Nelson Rolihlahla Mandela was a South African anti-apartheid revolutionary, political leader, and philanthropist who served as President of South Africa from 1994 to 1999.
The global icon was the country's first black head of state and the first elected in a fully representative democratic election. His government focused on tackling institutionalised racism and fostering unity.