What is the bill of rights and why did its omission from the original constitution raise such an outcry?

The Bill of Rights itself is the first ten amendments of the US constitution. Those that didn't want the federal government to have too much central powers and become oppressive, called anti-Federalists, wanted a bill of rights to guarantee that their rights won't be denied, because it would be listed in the first ten amendments. They are called unalienable rights.