The Big Five are the elephant, black rhino, leopard, lion, and buffalo. They were so named by hunters as they were arguably the most dangerous animals to hunt in Africa and perhaps the world. Now the term is simply used to denote these flagship species.
There is never a guarantee to see wildlife when one comes to Africa and goes on Safari. Some places, like the Ngorongoro Crater and Serengeti, however, one may see all the Big Five in one day. As there are less than 2800 black rhino left and they like to live in the thick bush, they are quite difficult to spot as are leopard. It really depends on luck when making sightings. The more game parks one visits and safaris one does, however, the greater the chances to see Africa’s animal wonders.