The alchemist mixes herbs, gathered by Herbalism, and reagents in order to generate elixirs, potions, oils, flasks and cauldrons with a variety of effects. A player can create healing, invisibility, elemental resistance and mana potions; oils to coat weapons; and much more Aion Gold.
Alchemy is useful to all character classes. Melee fighters can use alchemy to create buff and healing potions. Spell casting classes can use alchemy to create mana potions and related buffs. You can create potions for yourself, sell them to others, or give them to your party members and friends. Alchemists are well loved when they hand out potions.
With the price increase in herbs since Wrath was released its hard for Alchemists to make a profit, though some potions will sell well. Check prices on your server and eith gather your own herbs (to keep costs down) or keep an eye on the AH for screaming deals on herbs.