The 9th Amendment is one of the Bill of Rights and became part of the US Constitution when it was ratified on December 15, 1791. One of the concerns of those creating and ratifying the Constitution was that by stating rights in the Bill of Rights, it might be assumed that other rights not included were not protected. Thus, James Madison created the idea of the 9th amendment as a safeguard against abuses by future leaders. This amendment basically says that even if a right is not specifically listed in the constitution, this does not mean that it is not retained by the people at large.
Text of the 9th Amendment
The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people.