Why was the Bill of Rights added to the Constitution?

Bill of rights with reference to the US Constitution refers to the first ten amendments to it that specify and guarantee individual rights such as freedom of speech, religion, the press, and the rights to trial by jury and peaceful assembly. It became a law on December 15, 1791.

Bill of rights was incorporated in the US constitution in response to the the opposition to the constitution on the grounds that it did not specifically guarantee enough individual rights. Thus incorporation of Bill of rights in the constitution helped to obtain the ratification by all the states of the US Constitution itself.