The most important thing was to be able to be a market for the colonial masters. It was often the case that the colonial masters used the colonies as a market because they had a mercantilist policy.
They used the colonies to sell their goods, and often traded with them, such as slaves. Sugar and tobacco were important for the american colonies that europe took. Coming out of Africa, slaves were the main market.
They explored and colonized the new world for profit. There was loads of wood for shipbuilding, gold, and other materials found later (such as tobacco).
