Riding is a secondary profession in which characters may learn to ride mounts, which provide movement speed bonuses and, when applicable, the ability to fly. Increasing riding skill grants further increases to movement speed. All ground mounts increase movement speed by 60/100% (Apprentice/Journeyman) and all flying mounts increase ground movement speed by 100% and flying movement speed by 150/310% (Expert/Master).
More detail on the requirements for each mount can be found on the mounts page.
The following table lists the skill levels available and the cost to train each skill. Due to the high cost of training, the price with discount is also listed in the table. The only discounts available are faction discounts, which vary depending on where you train in the riding skill:
Apprentice and Journeyman riding are available from all riding trainers.
Demon hunters receive the 150 skill at character creation (level 8). They learn to summon a [Felsaber], a ground mount, as a quest reward in the Mardum starting zone.
Allied races receive the 75 skill upon character creation (level 10).
Note that like all professions, all lower ranked skill levels must be learned before training further (e.g. Expert skill is required to train Master skill).
This is a summary of the initial class mounts. Obsolete quests for the paladin and warlock mounts have since been removed from the game.
Artisan Riding no longer available from trainers. Characters who learned it prior to the squish retain the ability. Master Riding now requires Expert Riding as a prerequisite.
Newly created Demon Hunters now start with Journeyman riding (was Artisan Riding).
Learning [Running Wild], [Felsteed] or a Paladin class mount no longer automatically teaches Apprentice Riding.
Learning Flight Form no longer automatically teaches Expert Riding.
Characters that already had a 310% mount pre-4.0.1 are given this skill free of charge. All other characters must purchase Master Flying to receive 310% flight speed.
Changed the faction discounts for the riding skill vendors in Honor Hold and Thrallmar to use Stormwind and Orgrimmar faction, respectively. This is because newly-arrived 60s in Outland are unlikely to have any Honor Hold or Thrallmar rep.[1]
The cast time for summoning any ground mount is now 1.5 seconds, down from 3 seconds.
Apprentice Riding (Skill 75): Can now be learned at level 20 for 4. Mail will be sent to players who reach level 20 directing them to the riding trainer.
Journeyman Riding (Skill 150): Can now be learned at level 40 for 50. Mail will be sent to players who reach level 40 directing them back to the riding trainer.
Expert Riding (Skill 225): Can now be learned at level 60 for 600 from trainers in Honor Hold or Thrallmar. Faction discounts now apply (Honor Hold for Alliance; Thrallmar for Horde). Flight speed at this skill level has been increased to +150% of run speed, up from +60%.
In order to further equalize the number of purchasable mounts available to each race, a new 60% speed ground mount has been added for night elves, and a new 100% speed ground mount has been added for the undead.
Flying over Dalaran and Wintergrasp is now possible so long as players keep a healthy distance above the ground.
For 1,000 level 80 Main characters can purchase the heirloom [Tome of Cold Weather Flight] and give it to their alts level 68+ that have a flying skill of 225+ (not 150 as previously stated) to learn Cold Weather Flying.
Patch 3.0.2 (2008-10-14): Cold Weather Flying added at level 77 at a cost of 1,000.
Patch 2.4.3 (2008-07-15): The level requirement for Apprentice Riding was lowered from 40 to 30. It also reduces the cost from 90 to 35, and its respective reputation discounts.
Patch 2.0.1 (2006-12-05): PvP rankings also no longer grant the player an additional 10% discount
Before TBC, the cost of Journeyman riding was 900, so the total cost of getting an epic mount was the same as before. It has since been reduced to 600 to make it easier to buy Expert riding skill.
Hotfix (2006-09-28):We will be issuing rolling restarts across all realms [...] to apply a hot fix that will address an issue with mount riding skills. Players that had a mount in their inventory but were not given the appropriate riding skill should find that this has been corrected after this fix is applied.
Patch 1.12.1 (2006-09-26): The cost structure and functionality of Riding and Mounts was changed.
Prior to that patch, Riding was an ability rather than a secondary Profession, and had only one rank. Each faction had its own riding skill (tiger riding, horse riding, mechanostrider piloting, ram riding) and the cost was 20, available at level 40. Exalted reputation was required to learn cross-faction riding skill, but mounts were Bind on Use and purchasable by anyone for 80. This meant that characters who were PvP rank 3 or higher could pass on the 10% discount directly to other characters by buying the mount for them. This is no longer possible because all mounts are now Bind on Pickup, and the majority of the cost is built into the riding skill training (which is no longer faction-specific) rather than the cost of the mount.
Riding (Profession)
[Acherus Deathcharger], a ground mount, either as a quest reward in the Scarlet Enclave starting zone (non-pandaren core races) or automatically upon logging in (pandaren and allied races).
Death Knight
[Acherus Deathcharger]
Demon hunter
[Felsaber]
Paladin
[Summon Warhorse] (Human)
[Summon Sunwalker Kodo] (Tauren) 
[Summon Dawnforge Ram] (Dwarf) 
[Summon Darkforge Ram] (Dark Iron Dwarf) 
[Summon Lightforged Ruinstrider] (Lightforged Draenei) 
[Summon Charger] (Human)
[Summon Great Sunwalker Kodo] (Tauren) 
Warlock
[Dreadsteed]
Neutral Mount Trainers
