Final answer:
Decolonization is the process through which former colonies achieved independence from their imperial rulers, particularly after World War II. It marked a significant rise in the number of sovereign states, symbolized by increased membership in the United Nations.
Step-by-step explanation:
The period during which former colonies gained their independence from their imperial rulers is known as decolonization. This significant historical process involves the transition from being a colony under foreign control to achieving autonomous statehood, often characterized by membership in the United Nations. In the mid-20th century, a substantial increase in independent states occurred as a result of decolonization, shifting from a handful of sovereign nations before 1950 to over 190 member states in the UN today.
Colonialism, after World War II, had become unsustainable and faced with local resistance and nationalist movements, European powers, often realized the futility in maintaining their empires over determined local populations. The movement toward independence and self-rule led to the formation of new nations, especially seen in the wake of nationalistic fervor that spread across African and Asian colonies. France, for example, attempted reforms in its African colonies but was met with strong resistance that eventually led to independence movements and the subsequent end of colonial rule.