The reference to “Free Masons” occurs in the earliest documents. There are several suggested explanations for the meaning of this term. One is that they were workers in free stone and had the ability to shape it as they desired. The more logical meaning is that the workmen were free to move from one building project to another as they wished.
Upon completion of a particular building, each fellow of the craft would seek employment wherever it could be found. An apprentice was bound to a particular Fellow or Master and accompanied him to the new location. Prior to securing new employment, the Fellow would be examined on his knowledge, and have to exhibit specimens of his skill. It is very probable that he also would have to impart some sign or token of a secret nature to prove the Master that he had secured his knowledge and ability in a lawful manner, and was a worthy brother of the craft.Excerpted from: A History and Handbook, The York Rite of Freemasonry, by Frederick G. Speidel