Mentors comments:
The discussion is given in Old NCERT world history and its quite a common theme for discussion.

Discuss the backwardness of these nations, idea of transforming these areas into markets for the finished products from Europe, getting raw materials, weak political structure, displaced loyalties of natives, lack of modern army etc.

In a short segment, discuss the aftermath of imperialism once these parts became independent nation states. This will fetch you brownie points.

Answer:
Imperialism means the practice of extending the power, control or rule by a country over the political and economic life of areas outside its own borders. This may be done through military or other means, and particularly through ‘colonialism’ or the practice of acquiring colonies by conquest or other means and making them dependent. Most countries of Asia, including India, and Africa, and many other parts of the world were until recent years under the control of one imperialist country or another.

There were many conditions that helped imperialist conquest of Asia and Africa in the 18th and 19th Century:

The most important condition favouring the imperialist conquest of Asia and Africa was that the Industrial Revolution had not come to this part of the world.
The craftsmen produced goods of fine quality that Westerners admired and desired. But they relied entirely on hand tools which meant production on a small scale
In comparison with the production of Western countries in the nineteenth century, Asian and African methods were backward.
Also, because of the lack of knowledge that the Industrial Revolution had brought to the West, the two continents were militarily unable to stand up to the armed might and power of Europe.
The governments of the countries of Asia and Africa were very weak in the nineteenth century, though in ancient and medieval times powerful empires had existed there.
In the nineteenth century, the old ways of governing were still followed, even though they had outlived their usefulness.
Strong nation-states in the modern sense had not developed.
The people’s loyalties were still to local princes as in feudal times, or to tribal chieftains. These rulers cared little for the welfare of the people.
These conditions help to explain how small bands of Westerners succeeded in gaining power and, finally, with the backing of their governments, in conquering entire countries.

Effects of Imperialism even after 2 centuries:
The effects of imperialism in the life of the people in these country are still evident.
The most important and lasting consequence of imperialism and colonization was the economic backwardness of the colonies as well as of those countries indirectly controlled by the countries.
Imperialism also bred racial arrogance and discrimination. The idea of the superiority of the white race whom God had created to govern the world, was popularized in the imperialist countries.

By 1914, almost all parts of the non-industrialized Asia and Africa had come under or indirect control of a few industrialized countries. Most countries of Asia had lost their political freedom and were ruled by one or other country. The economies of all countries as well as of those which were politically independent were controlled by imperialist countries to serve rests. The imperialist countries took full advantage of these conditions and easily justified any and every conquest that served their interests. In fact, the more powerful nations made imperialism seem necessary and natural