Tank

Noun: Tank
Tanks are well-protected frontline party members whose role is to draw the enemy's attention (aggro) and attacks towards themselves as well as absorbing damage. They block their enemy's way and serve as meat shields for the spell casters and ranged attackers in the back lines behind them. They usually engage foes with melee or PBAoE attacks.

Warriors are the most common form of tank, having the strongest armor against physical attacks of any profession. Warriors have many skills (especially in the Tactics line) to help minimize damage and hold the enemies' attention. Other professions need to be more creative to mitigate damage and so are less common on the whole.

Warrior Tanks
A tanking warrior will come equipped with defensive tactics to mitigate as much damage as possible. Typically, the warrior will charge the enemy and will focus mostly on engaging the frontline, keeping mobs attention off other characters in the back row. Tanks use shields, stances and, sometimes, secondary profession skills such as Protection Prayers to minimize damage inflicted upon them. They can take quite a long while to kill. Tanks can be used as booby traps using AoE spells that are centered on the caster such as Inferno or Shield of Judgment, but should avoid skills that do damage over time as enemy mobs will run away.

Elementalist Tanks
Elementalists with high earth magic are more likely to have many enchantments that block or give armor, like for example: Stoneflesh Aura, Obsidian Flesh, Armor of Earth, Kinetic Armor etc.

Dervish Tanks
Dervishes that are designed for tanking will most likely carry several Earth Prayers skills, possibly an Avatar, and possibly some self healing. Such a dervish would use their enchantments and stances before battle, and attempt to keep them active while the battle occurred. Particularily common dervish armor tanking skills are Avatar of Balthazar, an elite form with a 40 armor bonus, and Conviction, a stance that adds armor when the dervish is enchanted, and health regeneration when not enchanted. Mystic Regeneration and Mystic Vigor are useful skills for recovering health.

Other Tanks
Some professions, given the right set of skills and proper preparation, can tank for their parties in certain areas. In particular, Rangers, Monks and Elementalists possess in their skill set a number of skills that can be used to make them very resilient to damage. These builds are usually attuned to the monsters in certain explorable areas that do not possess the means to overcome them. When the enemy is highly variable (as is the case in PvP), non-Warrior professions become susceptible to facing counters designed specifically for their means of damage reduction. For example, monks and elementalists relying on enchantments to resist attacks will have problems against skills that remove enchantments. Assassins can also tank with skills such as Critical Defenses or Flashing Blades.

Another popular non-Warrior tanking build is the Invincible Monk.

Using the expanded definition of "tank", it is also possible for pets and minions to tank for a team. This feature is used to great effect in the once popular Barrage/Pet builds (most commonly found in the Tomb ruins) that lack any damage-absorbing player characters.

Verb: to tank
Standing still and taking a beating from enemies instead of running away or kiting. Tanking is often used in PvE to make the healer's life easier (only one person to concentrate on). Tanking is especially effective in combination with Protection spells and stances.

It is important to be conscious of certain expectations while tanking:
 * Tank-on-Tank: This means that when assaulting an enemy group, the tanks should attract the aggro of the enemy melee fighters and keep it focused on themselves. Warriors who rush past the enemy warriors and head for the enemy spell casters make bad tanks because they allow the enemy warriors to get to their spell casters.
 * Aggroing Ranged Foes: Lets say the enemy melee units are blocked then killed and you are faced with the rest of the enemy units, casters/rangers that doesn't come close to you or the narrow place that you block, what you can try to do is either sidestep repeatedly left and right or again moving repeatedly forward and backwards, this way they will come close to you and get blocked.
 * No running back: While tanking, warriors should not, when the going gets rough, run back with their tails between their legs. Instead, warriors should trust their monks and if concerned, they should run sideways and/or dodge. Pulling enemies into the heart of your spell casters is a sure fire way to kill a few of them as well as get your monks in a panic which means they will not focus on healing you.
 * Keep tanks alive at all costs: A tank that has suffered multiple deaths and is running around with, say, 35% death penalty is of little use to the party in terms of tanking. The reduction to health greatly limits their ability to take damage.
 * Prevention is better than treatment: With the exception of facing enemy mesmers who Shatter Enchantments, a group is best served by using Protection Prayers on their tanks (along with healing) than by just trying to spam healing on them. Protection allows the monks to control the amount of damage inflicted on tanks and protects from the unexpected hit that suddenly kills a warrior.