The Articles of Confederation was a governing document that served as the "Constitution" for the United States for 8 years. It gave most of the power to each of the states, and almost none to the cetral government. This was to keep the central government from "choosing favorites" or becoming too powerful.
Shays's Rebellion highlighted the major weaknesses of The Articles of Confederation by helping the federal government realize that just those documents were not enough for a strong country, and that the United States needed a strong central government.
The U.S. Constitution, written in 1787 at the Constitutional Convention, replaced the Articles of Confederation.