When compared to the rest of the world, colonial Americans enjoyed a degree of self-rule that was found almost no where else.
Colonial government arose out of the need for timely leadership. The trip from the colonies to England took almost a month on average, and the innconvienance associated with having to wait months for responses from Parliment for every government decision was ridiculous.
As a result, a certain degree of self-government was granted to the colonies by the crown. Colonies could form assemblies which took care of day to day issues in the colony such as defense, taxation, and other buerocratic duties.
However, the king wasn't about to just hand over this power without any oversight. Therefore, he sent a representative to the colonial assembly who had to sign off all the decisions. This representative was called a governor.
For most of the 1700's this was the way of things. There were times in which assemblies were dissolved for taking too many liberties. (New York had their assembly removed then put back after a lengthy protest) But after 1763, the assemblies saw their power begin to be circumvented by direct Parliment control. Taxes were levied without their consent, which eventually led to the American revolution. Many assemblies lost their power when they lodged protests, which led to the first continental assembly in Philadelphia.