Night's 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."

- The Night's Watch oath

The Night's Watch is a military order which holds and guards the Wall, the immense fortification which guards the northern border of the Seven Kingdoms. It is led by Lord Commander Jeor Mormont from the stronghold of Castle Black.

The Night's Watch consists of three groups: the Rangers, who fight, defend the Wall and patrol the Haunted Forest; the Builders, who maintain the Wall and the castles; and the Stewards, who support and feed the members of the Watch.

History
Members of the Night's Watch swear an oath of duty that is binding for life and prohibits marriage, family, and land ownership. Desertion is a crime punishable by death. 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." Members of the Night's Watch aren't specifically forbidden from seeing their families, but they cannot leave the Wall without permission. First Ranger Benjen Stark would often visit his family at Winterfell while representing the Night's Watch.

According to legend, the Night's Watch was founded 8,000 years ago. They now protect the Seven Kingdoms from threats beyond their northern border but predate the Seven Kingdoms. They man a vast structure known as the Wall. The 700 foot tall barrier separates the Seven Kingdoms from the lands to its north. It is formed mostly from ice. The Watch have built several castles along the southern edge of the Wall to house their men. They also control a region south of the Wall known as the Gift. The region was donated to them by House Stark, the Kings in the North, at the time.

The Watch was once highly regarded and their ranks were filled with volunteers from noble houses. The institute has fallen into disrepute and faces disinterest from the throne. Their dwindling ranks are comprised of criminals avoiding corporal punishment or nobles avoiding scandal. Joining the Watch provides absolution for past crimes and immunity from further punishment. It also involves cutting ties to past allegiances and birthrights. Brothers start with a clean slate and can rise within the ranks whatever their origins. Dwindling numbers have caused the watch to abandon most of its nineteen castles along the Wall. Lord Commander Jeor Mormont now leads the Night's Watch from its stronghold at Castle Black, one of only three fortresses that are now manned along the Wall.

Based at Castle Black

 * {Jeor Mormont}, Lord Commander of the Night's Watch, Lord of Castle Black. Killed by Rast during the Mutiny at Craster's Keep.
 * Jon Snow, the Bastard of Winterfell, called "Lord Snow", personal steward to Mormont.
 * Benjen Stark, First Ranger. Missing north of the Wall.
 * Ser Jaremy Rykker, acting first ranger. Last seen at Castle Black.
 * Ser {Waymar Royce}, the youngest son of House Royce. A ranger killed by White Walkers.
 * {Gared}, a ranger killed by White Walkers.
 * {Will}, a ranger executed by Eddard Stark for desertion.
 * {Othor}, a ranger killed under unknown circumstances and raised as a Wight. Destroyed by Jon Snow.
 * {Jafer Flowers}, a ranger killed under unknown circumstances and raised as a Wight. Destroyed by members of the Watch.
 * Grenn, Rast, rangers. Status currently unknown.
 * Matthar, Balian, newly-made Rangers.
 * Aemon, maester at Castle Black.
 * Samwell Tarly, known as "Sam" and sometimes mocked as "Ser Piggy", personal steward to Aemon.
 * Bowen Marsh, the First Steward, currently at Castle Black.
 * Pypar, a steward, currently at Castle Black.
 * Hobb, steward and cook, currently at Castle Black.
 * Karl, Eddison Tollett, called "Dolorous Edd", stewards. Status currently unknown.
 * Othell Yarwyck, the First Builder. Joined the Great Ranging. Status currently unknown.
 * Halder, Toad, newly made Builders.

Based at the Shadow Tower

 * Ser Denys Mallister, commander of the Shadow Tower.
 * {Qhorin}, called "Qhorin Halfhand", leading ranger of the Shadow Tower. Killed in a duel by Jon Snow, per Qhorin's instructions.
 * {Harker}, {Borba}, {Stonesnake}, rangers led by Qhorin. Killed by the Lord of Bones' warband.

Based at Eastwatch

 * Cotter Pyke, commander of Eastwatch.
 * Borcas, head of the stewards at Eastwatch-by-the-Sea
 * Dareon, a steward, currently at Eastwatch.

En route to the Wall

 * Ser Alliser Thorne, former Master-at-Arms. Returning to the Wall with new recruits.
 * Lord Janos Slynt, former commander of the King's Landing City Watch and Lord of Harrenhal. Exiled to the Wall by Tyrion Lannister.
 * {Yoren}, a 'wandering crow' in charge of finding new recruits. Killed in the Riverlands by Ser Amory Lorch.

Recruitment
In the past, serving in the Night's Watch was a great honor and a sign of selfless devotion to the protection of the realm. In recent times, taking the black is seen by most of Westeros as a way of avoiding punishment. Recruiters known as wandering crows travel around the Seven Kingdoms gathering prisoners, orphans and other unwanted members of society and offering them escape on the wall. Yoren was a recruiter for the Watch before his death. Pypar and Rast are known to have joined this way, whilst Gendry  and companions were being taken to the wall for recruitment before their party was attacked.

Oath
When joining the Night's Watch, all members must swear the following oath, either in a sept if they are of the Faith of the Seven, or before a heart tree if they follow the Old Gods of the Forest.

"Hear my words and bear witness to my vow.  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."

Quotes
"The Night's Watch is the only thing standing between the realm and what lies beyond and it has become an army of undisciplined boys and tired old men. There are less than a thousand of us now. We can't man the other castles on the Wall. We can't properly patrol the wilderness. We have barely enough resources to keep our lads armed and fed."

- Maester Aemon to Tyrion Lannister

"You came to us as outlaws, poachers, rapers, killers, thieves. You came alone, in chains, without friends or honor. You came to us rich and you came to us poor. Some of you bear the names of proud Houses, others only bastard names or no names at all. It does not matter. All that is in the past. Here on the Wall we are all one House"

- Jeor Mormont to the recruits

"We've been guarding the Kingdoms for eight thousand years."

- Jon Snow to Ser Jaime Lannister

"Here, a man gets what he earns, when he earns it."

- Benjen Stark to Jon Snow

In the books
In A Song of Ice and Fire, the First Ranger is Benjen Stark, whilst the Lord Commander is Jeor Mormont, the father of Jorah Mormont. The Night's Watch is grievously under-strength by the beginning of the book series, having fallen from 10,000 when Aegon the Conqueror invaded to less than 1,000, divided into three garrisons at Castle Black (600 soldiers), the Shadow Tower (200 soldiers) and Eastwatch-by-the-Sea (less than 200 soldiers).

Of these 1,000 men, almost 300 are killed in the Great Ranging, due to the disastrous Battle of the Fist of the First Men and subsequent Mutiny at Craster's Keep. This further reduced the Night's Watches ranks to only 700 men, and perhaps worse, killed off most of their senior officers and best warriors, including Lord Commander Jeor Mormont himself. The expedition force consisted of one hundred men from the Shadow Tower and two hundred men from Castle Black.

Oath- The oath used in the show leaves out one line from the oath in the books.

''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 fire that burns against the cold, the light that brings the dawn, the horn that wakes the sleepers, 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.''

The Night's Watch has no heraldic symbol, to emphasize its sworn duty to be removed from petty politics of one lordly House or another, but to defend the lands of men as a whole. Thus, the Night's Watch uses solid black on its banner and shields, which symbolize the erasure of any allegiance to noble Houses. Even the "uniform" of the Night's Watch is to wear solid black clothing; members from wealthier families often buy all-black clothing before leaving for the Wall, while poor conscripts have their clothing simply dyed black when they reach the Wall (clothing which isn't always well-suited for cold weather). Solid black specifically denotes the rejection of heraldry, and is therefore strictly speaking not a "symbol" in and of itself, but the absence of a symbol.