GroundMounts are an assortment of creatures that provide a fast method of transportation. They can only be used on the ground. Ground mounts are stored in your pet bag and must be summoned to be used. While on a ground mount, you can only single jump and cannot attack.
Mounts have to be fed much like Venomancer pets. The higher the loyalty, the less chance that it will de-summon when hit by an enemy. Loyalty is increased by feeding your mount. Note that if you have a tome equipped, you will not need to feed it once 50%+ loyalty is achieved.
While you can buy a few mounts from NPCs in game, most ground mounts are bought with gold (using RL currency), but can also be bought from other places using coin (in game currency).
List of Ground Mounts:
http://pwi-wiki.perfectworld.com/index.php/GroundAirAt level 30, all races unlock the ability to fly using aerogear (also called aerocrafts or flying mounts). Winged Elves start at level 1 with the ability to fly but their wings consume MP with use. At level 30, all races can use the aerogear to fly without any penalty. In order for you to acquire your free level 30 aerogear, you must first go to the Elder of Archosaur and complete the quest he gives you. For all races, the quest tells you to go to your races' NPC and speak with them. That NPC will have you complete a task and after that, you are able to use your races' aerogear. Should you somehow lose or sell your aerogear you can purchase the default aerogear received in previous quest for 20,000 coins. You may also purchase aerogear from the Boutique, some of which will allow you to fly as early as level 10.
Aside from the level 30 quest to get a flying mount, you cannot get other mounts from NPCs in game. They must be bought with gold (RL currency) or from other players using coin (in game currency).
List of Flying Mounts:
http://pwi-wiki.perfectworld.com/index.php/Flying