Online:Skills

A player perusing the Skills menu|thumb|right
In Elder Scrolls Online, you advance your character by using different abilities, granted to you through different skill lines. In order to increase your progression in a skill line, you must use those skills. There are three types of skills: Passive Skills, Active Skills, and Ultimate Skills.

Passive Skills provide a bonus all the time. Some require certain items to be equipped or Active Skills to be slotted, but otherwise you don't need to think about them. They generally have a number of upgrades available, which can be acquired by increasing your level in the relevant skill line. In most cases, this is achieved by using the Active Skills within the same skill line. In other cases, such as crafting skills, this can be achieved via crafting items or research. Each upgrade costs an additional skill point. Some Passive Skills do not require an investment of skill points, but are instead provided free as a result of certain situations. For example, each race gets one free passive which increases their experience gain with a given skill.  The first level of each of the Crafting quality skills is free.  There are free Passive Skills associated with becoming a Werewolf or Vampire, as well as some provided by the keeps and resources owned by your Alliance if you take part in the Alliance War. All current Emperors also receive some free Passive Skills.

Active Skills are the ones you'll be using most in the game. You can have up to five slotted in your Action Bar, by default bound to the 1-5 keys. At character level 15, when you acquire Weapon Swapping, you gain an additional 5 slots for your alternate weapon. Like Passive Skills, they become available once a certain level in the skill line is reached. However, they cannot be upgraded, but rather improve through use. They have 4 Ranks, after which they may be Morphed into a new version. You will have two Morph options, which add different effects to the skill. Morphing a skill costs an additional skill point. Once a skill is Morphed, it can increase in Rank 4 more times, but may not be Morphed again (so you can't get both Morph bonuses for any skill). Using your Active Skills will increase your overall level in the skill line, making new skills become available as you progress.

Ultimate Skills are similar to Active Skills, but instead of using Stamina or Magicka as most Active Skills do, these use a third resource called Ultimate. Ultimate builds over time as you fight, and (with one exception) completely depletes when you perform an Ultimate Skill. No skill line has more than one Ultimate Skill, if it has one at all. Like Active Skills, they become available after a certain level in the skill line, raise in Ranks, and can be Morphed into new skills after Rank IV. You may only have one Ultimate Skill slotted at a time (two if you have Weapon Swapping after reaching level 15). By default it is bound to the 'R' key.

Class
Each of the game's classes has three skill lines associated with it, which are immediately available to your character and are specific to your class. To advance in the skill line, at least one active skill from the skill line must be slotted (as one of the regular five skills, or as the active Ultimate) on whichever of your two skill bars is in use at the moment of gaining experience points.



Weapon
There are six weapon skill lines, each linked to a specific type of weapon. These lines are:

Any class can advance in any of the Weapon skill lines, while using the appropriate weapon at the moment of gaining experience (whether that experience is gained by killing a monster, completing a quest or by any other means.)  Advancement will be faster by slotting one of the active weapon skills on your current skill bar (skills 1-5, or the Ultimate) when gaining experience points, with more slotted skills granting faster advancement.  If you have weapon skills from the "wrong" weapon slotted on the skill bar, the individual skills will gain progress (from I to IV), but the overall weapon skill will not (from 1 to 50).

Armor
There are three armor skill lines:
Light Armor
Medium Armor
Heavy Armor
Any class can advance in any of the Armor skill lines, while wearing the appropriate armor type. Only 1 piece need be worn, but progress will be faster the more pieces you wear of that type.

Racial
Each race has its own skill line. Your overall character level determines the abilities you may choose from your racial skills. See:


Progress in the Racial skill lines is directly equivalent to your character's overall experience level.

World
Not all of the skill lines are visible at the beginning of the game. You must discover other skill lines around the world, by completing certain quests, or finding certain items. The six World skill lines are:
Excavation   - obtained by the quest The Antiquarian Circle
Legerdemain - obtained by breaking the law
Lycanthropy - obtained by becoming a werewolf
Scrying   - obtained by the quest The Antiquarian Circle
Soul Magic - obtained by progress through the main quest
Vampirism - obtained by becoming a vampire

Guild
The Guild skill lines include lines for NPC guilds:
Dark Brotherhood 
Fighters Guild
Mages Guild
Psijic Order 
Thieves Guild 
Undaunted

Progress in the Guild quest lines (usually from 1 to 10 - the Thieves and Dark Brotherhood go up to 12) is done by doing guild faction quests, both in the faction's quest storylines and other repeatable quests (usually daily) that are related to the faction. In most cases (except for the Psijic Order which consists only of the quest storyline), you will HAVE to do some of the repeatable stuff to level your faction reputation up high enough to continue the storyline, or to level it up to maximum after the storyline is completed, because the storyline itself does not give you enough progress to reach the next stage of the quest storyline.

Fighters Guild progress is gained by killing undeads, Daedra or werewolves anywhere, and by doing daily quests to clear Dark Anchors. 
Mages Guild progress is gained by finding Lorebooks, and by doing daily quests involving finding relics in Public Dungeons.
Thieves Guild and Dark Brotherhood progress are made by doing repeatable quests (thefts or murders, respectively).  Some of these quests are daily, others can be repeated as often as you *like.
Psijic Order has no daily or otherwise repeatable quests, and progress is obtained only through the quest storyline.
Undaunted faction reputation is gained by clearing Dungeon quest storylines (once per dungeon), or by doing the daily Pledges from the three quest givers at the Undaunted Enclave, or by doing the daily solo delve quests given by Bolgrul at the enclave. The Undaunted have no overarching quest storyline.

Alliance War
Alliance War skill lines are the Player vs Player lines. These include siege weapons and other PvP abilities. Currently there are three Alliance War skill lines in the game:
Assault
Support
Emperor - a set of passive abilities possessed only by current Emperors

Progress in the Assault and Support lines comes as you gain Alliance War points for any PVP or alliance-war related activities - killing other players (in Cyrodiil, Imperial City or Battlegrounds), completing daily quests in Cyrodiil (both the war quests, and the PVE quests in Cyrodiil's various towns), capturing or successfully defending keeps and resources, capturing Elder Scrolls, and competing in Battlegrounds. Even getting Alliance Points from daily rewards from your ESO+ subscription counts towards Assault/Support progress on whichever of your characters is used to claim the reward.  You only need to reach about halfway from level 13 to 14 in Alliance War rank, to max out the Assault and Support lines at 10 each (they both increase together at the same rate).

Artifacts
In addition to the above, participating in the Alliance War has a chance to provide you with the use of certain unique Artifacts that grant you special powers:
Volendrung
Auriel's Bow (upcoming)
Sanguine's Rose (upcoming)

Craft
Crafting skill lines are each related to a profession and help boost the products you create in the related profession. These include:
Alchemy - which allows you to craft custom potions
Blacksmithing - allows you to craft custom melee weapons and heavy armor
Clothing - allows you to craft custom light and medium armor
Enchanting - allows you to craft custom enchantments to apply to your gear
Jewelry Crafting  - allows you to craft custom rings and necklaces
Provisioning - allows you to craft custom food and beverages
Woodworking - allows you to craft custom bows, staves, and shields

In all seven cases, you learn by doing it, and by completing the daily crafting writs once you have been certified as a craftsman of that skill. In the case of Blacksmithing, Clothing, Enchanting, Jewelry Crafting and Woodworking, you learn even faster by deconstructing found items (although you gain almost no progress from deconstructing an item you made yourself - however, you get full progress from deconstructing items made by another character, even if that other character is one of your own on the same account). The higher the quality of item you deconstruct, the more "inspiration" is gained towards that craft, especially if the item in question has the "Intricate" trait.  Alchemy and Provisioning have no Deconstruction, and Enchanting has no equivalent to the Intricate trait on worn/wielded equipment.

Dungeon
These skills are temporarily available as part of certain group dungeon mechanics:
Skeevaton
Werewolf Behemoth

Earning Skill Points
 
There are several methods of earning skill points, listed below, up to a current total of 481 points including all Chapters and other DLCs:
Leveling your character, up to level 50 (64 Skill Points)
Completing quests in the main quest (11 Skill Points)
Completing quest chains in the Dominion, Covenant, Pact, and Coldharbour main storylines (3 in Coldharbour: 16 in Covenant, 15 in Pact, 15 in Dominion)
Completing the Imperial City  storyline (1 Skill Point)
Completing the Reforging Orsinium  storyline (3 Skill Points)
Completing the Divine Power, Morag Tong, and House Telvanni quest chains on Vvardenfell  (3 Skill Points)
Completing the Summerset  storyline (3 Skill Points)
Completing the Elsweyr  storyline (3 Skill Points)
Completing the Greymoor  storyline (3 Skill Points)
Reading the Folium Discognitum (Optional quest reward from Mages Guild quest chain) (2 Skill Points)
Completing the primary quest chain of the Thieves Guild  storyline (6 Skill Points)
Completing the primary quest chain of the Dark Brotherhood  storyline (8 Skill Points)
Completing the primary quest chain of the Clockwork City  storyline (8 Skill Points)
Completing the primary quest chain of the Murkmire  storyline (7 Skill Points)
Completing the primary quest chain of the Dragonhold  storyline (9 Skill Points)
Completing the primary quest chain of the Markarth  storyline (9 Skill Points)
Playing or skipping the tutorial quest The Gates of Adamant or any previous Chapter tutorial (1 Skill Point - characters created prior to Morrowind cannot get this)
Absorbing skyshards (113 Skill Points in the base game: 46 more including all DLCs  (up to Markarth) and all Chapters    )
Ranking up in the Alliance War (50 Skill Points)
Completing group challenges in public dungeons (16 Skill Points in the base game, 10 more in expansions and Chapters - 2 each in Orsinium , Vvardenfell , Summerset , Elsweyr  and Greymoor )
Completing the story quest in group dungeons (24 Skill Points in the base game, one for each completed dungeon storyline quest: plus 20 more including those added by Imperial City , Shadows of the Hist , Horns of the Reach , Dragon Bones , Wolfhunter , Wrathstone , Scalebreaker , Harrowstorm , Stonethorn  and Flames of Ambition )
Completing Orsinium  Maelstrom Arena (1 Skill Point)

Spent skill points can be refunded at a Rededication Shrine for a fee of 50 Gold per point, or with a    available in the Crown Store. Note that the cost scales up with how many skill points you have acquired (including from Skyshards), and even if you only refund a single skill point and leave the others unchanged, you still have to pay the full cost (e.g. If you have acquired 10 skill points, you will have to pay 500 gold, regardless of how many skill points you want to refund). 

Unobtainable Skill Points
Three of the skill points listed above are unobtainable depending on your owned content and choices you make in the game.
2 Skill Points – become permanently unobtainable if you decide not to accept the Folium Discognitum in the Mages Guild questline.
1 Skill Point – unobtainable for any character created before the Morrowind chapter was applied to your account (due to not being able to complete the new tutorial quest or any of its chapter-specific predecessors).

Notes
As of patch 2.1.6 there were a total of 517 abilities, ultimates, morphs, and passives to spend skill points on for any given character, in the base game.  This assumes one Racial skill group, three Class skill groups (for one class), and all possible Weapon, Armor, World (including both Lycanthropy and Vampire), Guild, Alliance War, and Crafting skill groups.
Oddly, the Daggerfall Covenant quest line has 1 more skill point than the other two factions (16 instead of 15), due to there being 4 skill points available in Glenumbra, rather than the usual 3 per province. Not that this matters, since in the end, anyone can play through all three factions and get their skill points.
The Thieves Guild DLC adds 11 more options to spend skill points on.
The Dark Brotherhood DLC adds another 11 options.
The Summerset Chapter adds 36 more options between the Psijic Order and Jewelry Crafting lines.
The Greymoor Chapter added 27 more options between the Excavation and Scrying skills.
Despite the name, Riding Skill is not technically considered to be a skill.
When you have the Skills menu open, passing players will see your character reading a book with a brown cover.
 

 Skills