As Jon Snow and the Night's Watch have long warned anyone in Game of Thrones who would listen, Winter is Here. Finally, in episode 5 of season 7, "Eastwatch," Daenerys Targaryen believes the King in the North. However, Daenerys' council, including her Hand Tyrion Lannister, agreed that Daenerys' rival and current occupant of the Iron Throne, Cersei Lannister, would never believe their word that everyone in Westeros needs to cease their hostilities and combine their forces to wage war against the Army of the Dead coming from beyond the Wall.

In this week's episode "Beyond the Wall," a team led by Jon including Jorah Mormont, Gendry, Sandor Clegane AKA The Hound, Thoros of Myr, Beric Dondarrion, and Thorin Giantsbane headed into the winter lands north of the Wall. Their mission was to capture one of the undead so they can bring it back and show Cersei that the threat of the White Walkers is very real. This foolhardy endeavor of course meant Jon and his team would come face to face with the entire Army of the Dead led by the Night King, and it would be costly and tragic.

The White Walkers and the Army of the Dead are something Game of Thrones has not taken great pains to explain. Since they're regarded as a myth by the people of Westeros, very little is known about them. Not helping matters is that, as ice zombies, the White Walkers don't speak, and thus aren't prone to offering necessary details about their origins, functions, powers, and organizational structure. The general term 'White Walkers' tends to be applied to every type of undead creature coming from beyond the Wall. However, there are actually differences between the White Walkers and the foot soldiers that comprise the Army of the Dead, also known as the Wights. Here's what you need to know to survive the winter.

WHITE WALKERS

Led by the Night King, who was the first and most powerful of them, the White Walkers are a humanoid race of ice creatures. They are thousands of years old and possessed of powerful ancient magic. Like the Night King, they were created by the Children of the Forest to help them in their war with the First Men, but they broke free of the Children's control and became the greatest threat to all life in Westeros. However, they had faded into legend for hundreds of years, to the point where few in Westeros believe they are real.

The White Walkers tend to have long white hair, white beards, grey-white, mummified-looking skin, and glowing blue eyes. They are much stronger than humans, and they wield swords and spears made of what appear to be ice crystals. They have ice and cold-based powers, can create cold winds and frost to announce their imminent arrival, and they can freeze anything they touch. One of their most fearsome abilities is their power to reanimate the dead and turn them into Wights. They can turn not just dead humans, but animals like horses, bears and, as we found out in "Beyond the Wall," even a dead dragon into Wights.

The Night King himself has the power to turn humans into White Walkers; the Wildling Craster sacrificed his infant sons to the Night King, who would touch their foreheads and turn them into White Walkers.

The only known ways to kill a White Walker are with weapons made of dragonglass or Valyrian steel. White Walkers' bodies crack and fall apart when pierced by dragonglass, whereas Valyrian steel can instantly shatter them with a single blow.

WIGHTS

Wights are the undead; corpses reanimated by the White Walkers to serve as their army of foot soldiers. Wights can be both dead humans and dead animals; White Walkers ride undead horses into battle, and Jon Snow's company battled a bear turned into a Wight in "Beyond the Wall." Once turned into a Wight, the undead body shows no sign of rot or decay, regardless of what condition the corpse was in before it was transformed.

Wights lose their vestiges of humanity when they rise undead; they are unable to speak and it's unclear how much intelligence they retain or how much they can act independently of their White Walker masters. Unlike the zombies in The Walking Dead, however, the Wights can run and attack quickly, and are able to use weapons like swords. They have the same icy blue eyes as the White Walkers.

Wights can't be destroyed by conventional means of attack; even hacking off a limb or decapitation will result in the limbs still functioning separated from the main body. However, enough hacking and slashing will incapacitate a Wight from being able to attack. Fire is the Wights' weakness. The Wildings traditionally burned their dead to prevent them from turning into Wights. In "Beyond the Wall," Daenerys' three dragons burned legions of Wights with dragonfire.

Perhaps the most horrifying development yet occurred in "Beyond the Wall," when the Night King killed Daenerys' dragon Viserion with an ice spear. Later, he had the Wights pull Viserion's corpse from beneath a frozen lake with chains and then touched his head, turning Viserion into a dragon-Wight. What new powers Viserion will have as an undead servant of the Night King, and whether he will have any of the same vulnerabilities as the other Wights remains to be seen.

The death and transformation of Daenerys' dragon showed that even the greatest weapon the living have against the White Walkers can fall and be turned into a weapon against them. The biggest question to be answered in Game of Thrones is whether there is anything that can ultimately stop the White Walkers once and for all, or if Winter will ultimately claim all life on Westeros.

NEXT: WHY DAENERYS WON'T BECOME 'THE MAD QUEEN'

Game of Thrones season 7 concludes Sunday, August 27 @ 9pm on HBO, HBO GO and HBO NOW.