Why were the colonists opposed to the Stamp Act
and other acts that taxed
items in the colonies?

it was taxation without representation. the king, who keep in mind was miles across the ocean, was violating the colonists' right to be taxed without their consent. The French and Indian War left the king with a large war debt to pay. He tried to collect the money by placing taxes on the most common goods which only enraged the colonists. The colonies had no representation in parliament meaning that they had no one to represent their interests. Some interpret this as meaning that because the colonists have no spot in parliament, they are not consenting to be ruled. the colonies had set up their own form of government (because it was in their home and not miles across the ocean) and were abiding by its rules. then suddenly a king from across the ocean demands money from them. this was unfair to them because they had not consented to being taxed.