Just as the new applicant or "Entered Apprentice" progressed his way through the craft guilds in the Middle Ages by learning how to build cathedrals etc., so applicants to Freemasonry, who are also called Entered Apprentices, progress their way through our society by learning how to build character and so lead a better life. They do this through a dramatized series of lessons or ceremonies which we call "rituals."
Freemasonry uses the same tools in its rituals as the Operative Masons used to build cathedrals as tools or symbols in Character Building. Two of those tools are the square and compasses which together form Freemasonry's familiar "trademark" or emblem. The letter "G" in the centre, reflects the Masonic belief in God as the centre of all life.