According to the Merriam-Webster Dictionary, imperialism is "the policy, practice, or advocacy of extending the power or dominion of a nation especially by direct territorial acquisitions or by gaining indirect control over the political or economic life of other areas." European imperialism began in the sixteenth, century when explorers from Europe looked for new trade routes to the Far East, explored the Americas, and colonized North America, South America, and Asia. This time period is referred to as the era of Old Imperialism.
The era of New Imperialism began in the nineteenth century, when European powers established extensive empires in Africa, the Middle East, the Indian subcontinent, Southeast Asia, and China. These empires were set up in the wake of technological, scientific, and industrial advances brought about by the Industrial Revolution. The European powers that participated in both the old and new eras had several justifications for their imperialism.
Firstly, and above all, their motivation was economic. In the old era, European explorers plundered existing native civilizations for gold and other precious materials. In the new era of imperialism, subjugated nations supplied new markets for products, a cheap labor force, and raw materials for manufacturing that they could easily obtain and over which they could maintain control. In some instances, ruling European nations plundered materials from their colonies as brazenly as had explorers centuries ago, and cruelly treated natives as little more than slaves.
Another justification for imperialism was exploration and expansion. European nations wanted to discover unknown lands, conduct scientific and medical research, and win personal and national glory.
European nations also claimed to pursue imperialism for humanitarian and religious reasons. Christian missionaries set out to convert Native populations to what they perceived was the one true religion, the dominant religion of the empire. In doing this, they strove to teach Western values and Western culture. Many white people felt it was their obligation to "help" the non-white peoples of the world. This sentiment was brought out in the famous poem "The White Man's Burden" by Rudyard Kipling, in which he urges Great Britain and the United States to "take up the white man's burden" as a moral obligation and to help their subjugated non-white underlings, who were little better than "half devil and half child." This was connected with theories of Social Darwinism, which postulated that whites were inherently superior and should be dominant over weaker races.
Finally, imperialism was pursued by European powers for military and political reasons. In the viewpoints of the participating governments, national security necessitated having military bases in strategic locations all around the world. Having a powerful empire was also a source of national pride.