So you have probably opened this guide to learn what tanking in this game is and I shall give you a basic idea how to pull that off, so that your team will not have a reason to complain afterwards.
Nothing's more annoying than Healers arguing with Tank or anything inbetween.

I will cover a rather class neutral guide, so check other guides if you want in-depth info on your favoured class.

I am a screen-shot lazy person so this might get a little too text-based at times.

Note: I have quit the game between Shadowbringers and Endwalker, so information might be outdated. The general principles should still be viable and applicable however!

The tanks most valuable ressource, which is basically Aggro of monsters.
Everything in this game generates enmity, tanks just have the tools to generate more of it.

Healers generate enmity with their heals, Damage dealers of course with their attacks and Tanks with attacks as well.

Enmity is easily explained and also seen on the hud, the first element is the overview. It shows the enmity you have on monsters in combat. As a healer and tank, you should usually see all of the monsters, whereas as a damage dealer you often only see the monster you attack. When you have no enmity on a monster, it is not shown.

• Red means that you are currently being the monster's target.
  
• Orange means that you are close to getting the aggro.
  
• Yellow means that you have rather high aggro.
  
• Green means you have little to minimal aggro.

The second element is the Teamlist. It shows the Health, Mana and TP of your teammates and yourself. It also shows the enmity in detail of the monster you target.

• A means that you are the target of the targeted monster.
  
• 2 means that the healer is the second highest enmity holder.
  
• 3 is the 3rd highest holder with almost none.
  
• If a member is not listed means he has done nothing yet to generate enmity.

There is four different tanking classes, and each of them have a toolkit how to generate aggro which is rather similar. I will cover each classes' basic combo, AoE, ranged pull and Tank Stance.

With the expansion of Shadowbringers, they have tweaked how Enmity is generated by tanks. Now there's no dedicated combo to enmity, but rather a stance which massively increases generation.

From left to right it is always Gladiator, Marauder, Dark Knight, Gunbreaker.

Your opener. Use it once, and afterwards you will be able to follow with the next hit.

The follow-up. It deals bonus damage when you use it after the first hit. Avoid using this without the combo bonus!

The finisher of the 3-hit combo. As before, avoid using this without the combo bonus!

Your AoE. Total Eclipse, Unleash and Demon Slice have a range of 5y around you, while Overpower does a cone in front of you. Use these to ensure that you have enough aggro on every monster.

Your ranged pull. Use this to gain a headstart and aggro groups on you. Best used while you run up to the group and then follow up with AoE Pulls. Unlocks at level 15 - through the class quest.

Your tank stance, this is where holding enmity gets way easier. Basically, use this buff when being the parties' tank. Unlocks at Level 10.

As a tank, it'll come in quite handy to mark monsters. It is your tool to guide the party to focus what needs focus or just to help you tank better, as Damage Dealers focus the targets in order mostly.


By pressing SHIFT + M you open the Enemy Sign window which allows you to mark anything interactable with signs varying from Order from 1-5 to triangles and squares.
The use is pretty self explanatory, as you select the Mob/Thing to mark and press on the button for your desired mark.



These marks are shown to the whole party, but not always do people care, so please pay attention to what your party does!


While it's not the most clear looking thing when the mobs are bunched up, the smaller interface on the side, as mentioned above is a little easier to overlook:

Hitting level 30 is one of the milestones, that's the time when you should get a job.
To get a job you need your primary class on 30 for Paladin and Warrior or fulfill other prerequisites (see below). In this section I will shortly mention the quest names, locations and quest givers as well as their prerequisites.



To change your job you must have finished the Main Quest 'Sylph-management' and your previous class quests with the main class.


To become a Paladin, originating from the Gladiator, your Quest 'Paladin's Pledge' will be in Ul'dah - Steps of Thal (X: 9 Y: 11) (the Gladiator Guild) at Lulutsu, the receptionist.


To become a Warrior, originating from the Marauder, your Quest 'Pride and Duty (Will Take You from the Mountain)' will be in Limsa Lominsa Upper Decks (X: 11 Y: 6) (the Marauders Guild) at the guild master.


To become a Dark Knight, you must have finished the main quest to the point where you unlocked the town of Ishgard. Your quest 'Our End' is located at Ishgard, The Pillars (X:13 Y:8) at the Ishgardian Citizen.

To become a Gun Breaker, you must have purchased the Shadowbringers Expansion and have a Tank/Healer/DPS on Level 60. Your quest The Makings of a Gunbreaker is located at Gridania (X: 11.5, Y: 11.9) at the Gods' Quiver Bow.

This covers the low level as tanking is something everybody develops his own style for.

If you are new in the dungeon; do not hesitate to communicate! Ask your party members for hints and strategies on bosses if there is something etc.

Else there is a basic guideline in dungeons which you should usually follow unless you are told / experienced it to be done differently:

That includes both bosses and 'trash'.

Trash:
Trash is basically everything in dungeons which you have to kill while moving through the dungeon.
If it is a group of monsters, 2 - x, you use your Ranged pull on one mob - preferrably the first target to kill - so all the monsters charge on you. Engage the group while doing so, and start using your AoE about twice or three times. Be sure that you hit all of the monsters. If they are too spread, consider using another Ranged pull on the furthest mob. Given you have got your AoE off on every mob (you can see by their names changing from yellow to red), you should check what your DDs in the party are doing; if they attack Mob A, you'd do your best doing your combo on the monster, keep throwing in AoEs now and then since Healers generate Enmity with every heal. If the DDs decide to attack different mobs, use AoEs and alternate with the combo on the two mobs.

If it happens to be a single monster, you can basically engage on it like you'd do on a boss which I will explain below.

Also, do not hesitate using Buffs. Most of them have 90 - 180 cooldowns and while that sounds much, think about the fact that you're likely spending 15-30 minutes in one. You just shouldn't use the cooldowns when you are shortly before a boss.

Bosses:
I think I do not have to explain what a boss is, but it is basically the big guy or the little big guys guarding the way to the big guy.

To engage him, preferrably use a ranged pull on him, then follow up with your first combo hit while running through him so you end up behind him and he turns away from the team. Of course, this is general speaking so you should consider asking first if there is a special way you have to tank the boss. If not, try to keep the boss facing the other way, away from your team so they do not take unnecessary AoE damage. During the boss fight, focus on keeping his aggro with the combo and dodging any AoEs he throws at you. Some trigger automatically, I am talking about the ones you actively can dodge. Just because you are tanky doesn't mean you should take damage you can avoid. Glowing ground is in 95% cases something harmful, so get out of there.
Of course, little big guys and the big guys themselves love themselves even more little guys and that's Adds. As a tank, it is almost always your task to keep the aggro of these, so you try to lure them to you by using your Ranged Pulls. After you have amassed them, throw in a lot of AoEs so they will stay focused on you while the DDs take care of them. During these times, you should throw in defensive buffs so the healer does have a small time window of healing you. When you die, there's a fustercluck. Don't let that happen.

I strongly recommend you to recognize boss patterns you see. If you are unfamilar stick to the rule of asking. Often you will just hear the following: Kill adds, dodge AoE.

If you are struggling to keep aggro of a monster that is okay on low level, and can often happen e.g. DD attacking a different monster than you and you are already struggling to keep the other mob.

Measures against that are basically all the things that make you deal more damage or heal yourself. So throw in damage buffs, use AoEs and your Combo. Getting aggro back is way harder than gaining and keeping aggro, let me tell you that. Especially ranged ones love to kite, making it nearly impossible for you to land melee attacks on the monster.

Provoke is THE skill to get it back. It will give you the currently highest enmity + a small value so it doesn't immediately snap off again.

If you find yourself struggling despite all that, do not hesitate to communicate and begin using marks to signal your DPS to focus the target you also focus on.

Oh... and make sure you are in your stance. (It will happen.)

As soon as you start running into dungeons at a higher level, chances are you will end up with 7 other players and among them, you might find another tank.

MT: Main Tank; the person who will take care of the boss.
OT: Off Tank; the other tank who takes a more DPS oriented role and takes care of various things which differ heavily depending on the content. This can include but is not limited to: taking care of adds, using cannons and LASERS.

As with many things in multiplayer games, communication is key! Make sure that you speak with the other tank and make your roles clear. If they by chance do not reply and stay in tank stance, just assume the role of an Off Tank. Of course, if they do not go into Tank Stance, then you shall assume that role.

Seriously. Press this even though the MT has the monster and there's no reason to provoke, I will hire a hitman to find you.


Some mechanics force the tanks to swap their MT and OT roles respectively. This can have many different reasons such as vulnerability stacks, LASERS, etc...

The process is fairly simple and usually is consisting of several steps:
1) The Boss is charging up the mechanic/hit the mechanic that will affect the MT.
2) Either during the charge or after it hit, the OT provokes the Boss.
3) The MT will use Shirk on the OT and transfer his enmity.
4) During this time, the OT takes the position of the MT and the MT takes position of the OT.
5) Depending on the fight, MT and OT swap back, so proceed with the previous steps as needed.

tl;dr: OT provokes, MT shirks OT

Shirk is a wonderful spell that lets you divert 25% of your Enmity to another target, which should be the provoking Tank (unless you really hate a DPS and want to kill them.)

Basic Paladin info:
https://na.finalfantasyxiv.com/jobguide/paladin/

Basic Warrior info:
https://na.finalfantasyxiv.com/jobguide/warrior/

Basic Dark Knight info:
https://na.finalfantasyxiv.com/jobguide/darkknight/

Basic Gunbreaker info:
https://na.finalfantasyxiv.com/jobguide/gunbreaker/

25.12.2015 : Just created a changelog, too lazy to list edits from before.
25.12.2015 : Added 'STR or VIT' section as suggested by Hollow - ホロー.
04.01.2016 : Added a tl;dr to the 'STR or VIT' Section.
11.02.2016 : Updated the 'STR or VIT' Section as of changes in Patch 3.2
07.07.2016 : Added a 'Marking Mobs' Section.
08.07.2017 : Updated the guide to be a bit fresher for Stormblood: Removed the Cross Class Skill section as of the Role Skill rework, changed the note on the 'STR or VIT' section.
27.03.2018 : Secondary classes became obsolete, updated the "Getting a Job" section.
10.07.2019 : Redone the guide to fit Shadowbringers changes, removed STR or VIT section, added section for 2nd Tank.

Alright we gotta stack left here, NO WAIT RI- - Xeyron 1996 - 2018

Joke aside, I am a Raid Tank and I have seen a LOT of people not tanking properly on higher levels even. This guide may be a little too little in detail and in other places maybe too much but I think the provided info should help whoever reads this to get a grasp on how to tank.

I hope you enjoyed reading this rather text heavy guide and as stated before, Tanking is a lot of intuitive work, so just keep playing and learn what's working out best for you!

I will try to update the guide here and there as needed when I find the time, and I appreciate any kind of feedback you have for me!