As it attracted the elite of Joseon officialdom, the Three Offices provided one of the fastest routes of promotion to top posts in the Royal Court and was almost a requirement to becoming a State Councillor.
Together they were called "Yangsa," (양사) which literally means "Both Offices," and often cooperated in joint actions especially when they sought to reverse the king's decision.
In their role as organ of press, they did not have actual authority to decide or implement policies, but had influential voice in the ensuing debate.
[2] It oversaw the royal library and served as research institute to study Confucian philosophy and answer the king's questions.
Its officials took part in the daily lessons called gyeongyeon (경연), in which they discussed history and Confucian philosophy with the king.
More significantly, Three Offices developed into a third base of power that provided checks and balance between the king and the ministers of State Council and Six Ministries.
Again, Sarim scholars led by Jo Gwang-jo used Three Offices as power base to challenge Hungu ministers and launch a series of reforms.
However, Jungjong was estranged from Jo Gwang-jo due to radical nature of his reforms and slander of the Hungu faction, which led to Third Literati Purge of 1519.