NPC stands for Non Player Character. These are scattered throughout the world of Aincrad.
These NPCs are often found in cities or towns. They can sell various items such as food and teleportation crystals. They will also buy items from you, though selling equipment is currently bugged.
In the Town of Tolbana, there is a merchant that sells teleportation crystals
These NPCs are also found in towns or cities. They will craft you a weapon or armor for a price depending on the type of material you request to be used in crafting. They can currently craft all the different weapon types. Blacksmiths can also craft light and heavy metal equipment, but not leather. The Blacksmiths can also craft equipment of different rarity, though it is entirely random.
Weapon Materials Edit
Armor Materials Edit
These NPC give quests. These quests don't work currently and should not be accepted.