Star Trek: Section 31 – What the heck is it, and why does it appear in Star Trek: Discovery?
If you've watch the previous week's Star Trek: Discovery's episode called "Point of Light", you may have noticed a new ship and badge at the end of the episode. The ship and badge are from a less-known non starfleet organization called Section 31.
What IS Section 31?
Section 31 is an officially non-existent autonomous intelligence and defence organization. It is presented as a special security operation, manned by Federation citizens, that is not subject to the normal constraints of Starfleet ethical protocols.
The organization is introduced to canon in Deep Space Nine, with appearances in additional episodes of Deep Space Nine, as well as episodes of Enterprise and Discovery, and the 2013 film Into Darkness.
In the Star Trek storylines, Section 31 operated separately from and usually without the knowledge of Starfleet Intelligence. It dealt with threats to Earth's and, later, the Federation's security. Its operating authority stems from a provision of the original Earth Starfleet charter—Article 14, Section 31, from which its name is derived—that makes allowances for "bending the rules" during times of extraordinary threats.
Unlike other secret police organizations in the Star Trek universe, such as the Romulan Tal Shiar and the Cardassian Obsidian Order, Section 31 is not an actual branch of government. Accountable to no one, Section 31 focuses on external threats, and pursues those it identifies by whatever means it sees fit.
Little has been shown in the Section 31 world. But that will hopefully change with the recently announced spin-off featuring Star Trek: Discovery's Michelle Yeoh playing as Philippa Georgiou.
Additional Source: Wikipedia