The Federalist Papers by Alexander Hamilton, John Jay, James Madison  is a collection of 85 articles and essays written by Alexander Hamilton,  James Madison, and John Jay under the collective pseudonym ’Publius’ to promote the ratification of the United States Constitution. The collection was commonly known as 
The Federalist  until the name 
The Federalist Papers emerged in the 20th century.
The first 77 of these essays were published serially in the 
Independent Journal, the 
New York Packet, and 
The Daily Advertiser between October 1787 and April 1788.
A compilation of these 77 essays and eight others were published in two volumes as 
The Federalist: A Collection of Essays, Written in Favour of the New Constitution, as Agreed upon by the Federal Convention, September 17, 1787  by publishing firm J. & A. Mc Lean in March and May 1788.
The last eight papers (Nos. 78–85) were republished in the New York newspapers between June 14 and August 16, 1788.