Initially, Britain's Navigation Acts provided the colonies with a built-in market, which kept both sides happy and profitable. It wasn't until after the French and Indian War in 1763 that Britain attempted to change its policies on mercantilism, and began enforcing policies that led to the animosity between Britain and its colonies.
The purpose of the Navigation Acts was to limit colonial trade to Britain only. If the colonies wished to trade with anyone else, they had to go through England first. This policy allowed England to collect revenue from taxation. However, there were certain products that the colonists could only trade with England. Initially that was cotton, tobacco and sugar but, in time, that list grew and continuously decreased the number of goods the colonists could trade with other countries.