Countries were classified as first, second , and third world during the cold war based on their membership to either NATO or Communist bloc; therefore, the first member countries were classified as the first world, whereas the second countries were called the second world, while the ones that are neutral or not members were classified as the third world. During the cold war, this classification was basically political, and not all African countries were third world countries even though the majority were.
After the cold war, the classification of countries as first, second, and third became meaningless because as at that time, first world countries basically meant rich countries, while third world meant poor countries. Nowadays, countries are classified based on their economic development, which are developed and developing countries. And now not all the countries that were seen as first world countries during the cold war are developed countries now. Hence, Africa is a third world or developing continent due to its less developed economy as compared to that of Europe and North America.
Africa even though has the largest number of countries with the fastest growing economies, also has the largest number of poor countries and has been a third world continent due to low level of productivity, high level of infant mortality, lack of clean water, and poor infrastructure. Many Asian countries were also third world countries just like Africa, but were able to make a transition from third world to first world. For example, Singapore became a developed country in just a generation, which indicated that many African countries are well placed to make this transition if government makes significant steps to achieve certain results.
Most African countries such as Gabon, Ivory Coast, Ethiopia, South Africa, etc., have a great chance of becoming first world countries if correct measures are taken, from human development by improving household incomes, to state intervention and creating great infrastructure.