Source: http://gameofthrones.wikia.com/wiki/Night%27s_Watch






Night gathers, and now my watch begins. It shall not end until my death. I shall take no wife, hold no lands, father no children. I shall wear no crowns and win no glory. I shall live and die at my post. I am the sword in the darkness. I am the watcher on the walls. I am the shield that guards the realms of men. I pledge my life and honor to the Night's Watch, for this night and all the nights to come.

History :
According to legend, the Night's Watch was founded 8,000 years ago.[2] They now protect the Seven Kingdoms from threats beyond their northern border, such as White Walkers, wildlings and giants. They man a vast structure known as the Wall, a 700 foot tall and 300-mile long barrier which separates the Seven Kingdoms from the lands to the north. It is formed mostly from ice with small trenches and wooden fortifications covering the top. The Watch have built nineteen castles along the southern edge of the Wall to house their men, however, over the years many were abandoned. They also control a region south of the Wall known as the Gift, from which they obtain supplies and provisions. The region was donated to them by House Stark, the Kings in the North, at the time.[3][4]

Members of the Night's Watch swear an oath of duty that prohibits marriage, family, and land ownership which lasts until their death. Recruits renounce all past allegiances and birthrights. Joining the Watch provides absolution for past crimes and immunity from further punishment. Brothers start with a clean slate and can rise within the ranks whatever their origins.[4] However, even though the Night's Watch vows are meant to be for life, it is possible for one to leave the organization without execution, so long as it is with the ruling monarch's approval. For instance, Stannis Baratheon, a claimant to the Iron Throne and the King in the Narrow Sea, offers Jon Snow a chance to leave the Night's Watch and serve him in exchange for legitimization, though this may partially be due to the fact that the Night's Watch is not taken as seriously by most as it once was, and Stannis was desperate enough to turn to Jon Snow for aid.[5]

They describe one another as "sworn brothers" because of the oath. Men of the Watch dress entirely in black, giving rise to the nickname "crows" - which is what the Free Folk commonly call them - or "black brothers."[3] Members of the Night's Watch are not specifically forbidden from seeing their families, but they cannot leave the Wall without permission. Desertion is punishable by death. First Ranger Benjen Stark would often visit his family at Winterfell while representing the Night's Watch.

Castle Black.jpg
Castle Black - largest of the three occupied castles.
The Watch was once highly regarded and their ranks were filled with volunteers from noble houses, as serving was a sign of selfless devotion to the protection of the realm.[citation needed] However, while the Night's Watch still has noble-born sons and noble-blooded illegitimate sons from Great Houses, many recruits are now also criminals avoiding punishment, nobles avoiding scandal, orphans, and other social outcasts. Men known as wandering crows, such as Yoren, travel around the Seven Kingdoms gathering recruits for the Watch, offering them escape on the Wall. For some families, the Wall is a convenient place to exile embarrassing or disgraced family members. Samwell Tarly was disowned by his own father and ordered to join the Watch on threat of death, while Tywin Lannister had plans to exile his own son Tyrion to the Wall so as to avoid executing him for allegedly murdering King Joffrey Baratheon. However, other families, such as House Stark, view the Night's Watch as an honorable and noble calling. Generations of Starks have joined the Night's Watch for the sake of honor.[6]

By the reign of King Robert Baratheon, the institution has fallen into disrepute and is largely ignored by the throne. It is severely undermanned; dwindling numbers have led to all but three of the Wall's nineteen castles being abandoned. The Night's Watch is now led from its stronghold at Castle Black.[3] The Shadow Tower and Eastwatch-by-the-Sea are the only other castles that are still manned. Meanwhile, trouble is stirring beyond the Wall. A large wildling army under a new King Beyond the Wall, Mance Rayder, is advancing south, and there are rumors that the White Walkers, long since thought to be extinct, have returned. At the time Jon Snow arrives at Castle Black, the Lord Commander of the Night's Watch is Jeor Mormont.

The Night's Watch is more egalitarian compared to the rest of Westeros, and at the Wall, every man is given what he earns. No matter their status, recruits can become high-ranking officers and commanders for their service. However, the Night's Watch is not completely egalitarian as both noble-born sons and illegitimate sons of lords are favored for advancement over those with no noble blood.[7]


Organization:
Men of the Night's Watch are divided between three different orders: the Rangers, the Builders, and the Stewards. Each order is led by its own officer, each appointed by the Lord Commander of the Night's Watch: the First Ranger, First Builder, and First Steward.

Rangers - the true warriors of the Night's Watch. While all black brothers are expected to have some basic arms training and to take up a sword in defense of the Wall itself, the Rangers are the ones who are sent on dangerous scouting expeditions beyond the Wall, to track wildlings movements. When the Watch was more numerous in past centuries they formed the core fighting group sent to destroy large wildling warbands who attempted to pass south of the Wall.
Builders - who physically maintain the structures of the Night's Watch, and repair the Wall itself.
Stewards - who provide for the day-to-day needs of the Watch: gathering, cooking, and serving food, repairing clothes and equipment, tending to the horses and messenger-ravens, and gathering firewood. By far the largest of the three orders.
Each castle of the Night's Watch also has a maester assigned to it. These maesters take the oath of the Night's Watch and are considered full black brothers, but are not considered part of the three orders. Given that there were never more than nineteen castles along the Wall, there were never more than nineteen maesters in the Night's Watch at any one time. Since there are only three active castles on the Wall in modern times, there are now only three maesters in the Night's Watch at a time.

Leadership
The leader of the Night's Watch is the Lord Commander. Each Lord Commander serves for life, and a new Lord Commander is democratically elected by other members of the Night's Watch in a Choosing.

It is unknown if there is any formal procedure to depose a Lord Commander and elect a new one, in cases where the current Lord Commander violates his oaths or is deemed medically unfit to lead, etc.

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