American colonists protested the Stamp Act of 1765 because it was a tax imposed on them by the British Parliament instead of their elected colonial legislatures. They believed it was unjust to be taxed without their consent by unelected rulers.
The Stamp Act mandated that all printed material in the colonies be produced on paper from London embossed with a revenue stamp. It was the first direct tax on internal colonial activities levied by Parliament. The American colonists responded to the tax with vigorous, and sometimes violent, protests. Parliament repealed the Stamp Act in 1766 but also passed the Declaratory Act, which affirmed its right to tax the colonies "in all cases whatsoever."