Question

As the European powers grew more industrialized their colonies became very important as a source of what?

Answer 1

For future reference, I'd ask you post this in the "History" subject, but I'd be happy to help if you still need it. When colonies were being founded, one hugely-important thing was being found literally everywhere - raw resources. A huge problem that many of the host countries had was the fact that they had used up all the natural resources over time. This meant that they had to import in raw resources such as lumber and some crops (The colonies having better climates for growing plants such as tobacco.) The colonies would have been obliged to provide the host countries with at least part of the revenue of exporting such valuable natural resources, or could have even just shipped the resources directly home, to be used possibly free of charge (shipping costs notwithstanding).
If you have any more questions concerning history, feel free to mention me with "@noseboy908".