Tank

Noun: Tank
Tanks are well armored front row party members whose role is to draw the enemy's attention and attacks towards themselves as well as absorbing damage. They block their enemy's way and as such serve as meat shields for the spellcasters and Ranged Attackers in the back lines behind them. They usually engange foes in melee or PBAoE attacks.

Warriors are generally the best tanks, mostly because of their superior armor and their massive melee damage output. Infact many GuildWars players use "tank" and "warrior" as almost equivalent terms and think of a warriors exclusively when they ask for a tank. However, other professions may take over the role of a tanks as well, although they are more vulnerable and less suited for it. Scroll down for details.

Note: "Tank" is also used as a verb "to tank", which simply means to act as a tank.

Note: The antonym of a tank is a "squishy".

Offensive Tank
A warrior specialized in heavy damage dealing. His/her primary focus is engaging the biggest threat in the enemy and quickly rendering it lifeless. His tools include knockdowns, bleeding and deep wounds. An Offensive Tank's biggest fear is hexes like Empathy that cause an attacker to lose health as well as negative conditions like Blindness that cause an attacker to miss.

Defensive Tank
A warrior fortified with all possible defensive tactics to soak up as much damage. A Defensive Tank will charge the enemy but will focus mostly on engaging the frontline of the enemy and keeping them busy fighting him/her. Defensive Tanks will use shields, stances and -if applicable- Protection Prayers to minimize damage inflicted upon them. They can take quite a long while to kill. Defensive Tanks can be used as booby traps using AoE spells that are centered on the caster such as Symbol of Wrath, or Balthazar's Aura.

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 posses 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 posses the means to overcome them. A Ranger relying on stances to dodge attacks will have problems taking on elementalists while a monk or elementalist relying on enchantments to resist attacks will have problems facing mesmers and certain necromancers.

Some popular non-warrior tanking builds include:
 * Invincible Monk
 * Invincimentalist

Verb: to tank (incl. Tips)
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's 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 tanks and keep it focused on themselves. Warriors who rush past the enemy warriors and head for the enemy spellcasters make bad tanks because they allow the enemy warriors to get to their spellcasters.
 * 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 spellcasters 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 aroud with, say, 35% DP is of little use to the party in terms of tanking. The reduction to health greatly limits their ability to take damage. As a monk, if you have to choose between healing the tank and healing an elementalist, keep the tank alive. The elementalist can operate with 35% DP from the back if the tank is doing his job, the inverse is not true. A warrior who does not tank and instead rushes off to kill enemy spellcasters forfeits that privilege.
 * Prevention is better than treatment: With the exception of facing powerful 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 thus protects from the unexpected hit that suddenly kills a tank.