What is meant by Imperialism? Why was it an important cause of the First World War?

Imperialism refers to the state policy or practice by which a powerful nation establishes its control over another country, either by direct territorial acquisition or by gaining political and economic control.

By the end of the 19th century, England and France had built up a huge colonial empire in Asia and Africa. Other countries like Germany, Italy, Russia and Japan also wanted to increase their sphere of influence and create their colonies in Asia and Africa. This led to a clash of interest among these countries. They began to scramble for colonies which resulted in secret alliances, rivalries and wars ultimately leading to the First World War.