After the Constitution was ratified, the first Congress was held. Most of the delegates agreed that a Bill of Rights was needed and most of them desired the same rights. The task of drafting the Bill of Rights fell to James Madison. It had been decided earlier that the Bill of Rights would be added to the Constitution as amendments (the list of rights was not included in the Constitution itself because it was feared that changing the document would necessitate the rather painful process of re-ratifying the Constitution).
The Bill of Rights includes rights such as freedom of speech, press, religion, and assembly. It also includes a clause assuring the American people that the bill of rights does not list EVERY right given to Americans, but rather lists the most important rights.