| The Original Use of the Word The contemporary use of the word is recent. In the 19th century it was used to discuss the general condition of overseas dependencies or the colonial system as a whole. But it had no specifically favourable or unfavourable meaning. In the British public mind it was associated with places such as Australia rather than non-dependency colonies. Hence as the British Empire expanded in the late 19th century the whole colonial organisation came under the banner of Imperialism.
When and Why it began to changeIt was in the 1950s that a distinction began to be made between Imperialism and Colonialism. As Imperialism came under a more specific Marxist definition, Colonialism came to be the description of the state of subjection (political, economic and intellectual) of a non-European society which was the product of Imperialism.
So what does Colonialism refer to?Colonialism refers to the condition of a subject people. It emphasises that the dominant group is alien and remains so. There is no necessary common interest for the rulers and the ruled. Colonized areas were given a wide autonomy which in the case of the British Empire led to sovereignty within the British Commonwealth. On the other hand Europeans in tropical colonies tended to view them as places of work only, would remain alien and tended to return home for retirement.
This means colonialism represents exploitation by the foreign society and its agents to serve their own interests. This had nothing to do with the interests of the subject people. Further it is usually thought Imperialists attempted to destroy the culture of the dependency and replace with their own: Cultural Imperialism. So not only was a society deprived of its wealth and freedom but also of its character.
Problems for a historian
This emotive definition of Colonialism as arisen because it is almost entirely used by opponents of colonial rule. This is similar to how Imperialism was given its current meaning by those who saw it as one of the most unlikeable consequences of modern capitalism.
But there is another approach! Those who denounce colonialism have three basic assumptions. First, that there was a better alternative available at the time. Second, that the undesirable features were deliberately intended by the Imperialists. Thirdly, that the effects were universally deplorable. This is a very controversial issue in the post-colonial world. But it is an historian's duty to look at colonialism in its context. Hence:
"Colonialism must be seen in its context as one aspect of a particular, largely unplanned and, as it turned out, transient phase in the evolving relationship between more and less developed parts of the world in the century after 1870" (D.K.Fieldhouse).
This does not mean one should become an apologist for Colonialism. But it does indicate the problems that we all face when dealing with emotive and controversial issues. In this case, although one may feel something is wrong with Colonialism it should not detract from a comprehensive assessment of the it. So historians are left with the task of assessing colonialism and the degree to which it was bad or good for the people involved.
Now what this ultimately leads to is an appreciation of the importance of the assumptions one makes when undertaking such an assessment. In this case it hinges on whether one values modern economic development. If one does then suddenly Colonialism becomes far more acceptable. If not it remains an outrage. Yet this helps show the problem the word has for historians. It is emotive and hence itself provides a basis of discussion! | 
