1. because they bought modern in-frustration,consumables and culture to the poor Africans ,which greatly boosted their standard to live.

2. negative side said to be that the African has to deal with discrimination /racism  and violation against their human right.but the lot of colonies choose to work for the imperial power.there were also a lot  of wars, and it was often costly to conquer and maintain the colonies.

anyways........according to my logic it was rather positive (IMO) but from what I've been told the negative outweigh the positive ones.
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