The Alchemist mixes herbs in order to generate potions with a variety of effects. A player can create healing, invisibility, elemental resistance, and mana potions; oils to coat weapons; and much more.
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. Alchemy is a fun Profession where 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.

Becoming an Alchemist

First, you need to find an alchemy trainer. You can ask a guard in a big city to find a trainer if you're lost.
You don't need any special equipment or devices beyond the required reagents. Alchemy always requires flasks to make potions. There are four flasks: Empty, Leaded, Crystal, and Imbued. You can make potions anywhere.

Gathering Ingredients

If you wish to be an Alchemist you should already be an Herbalist. It is possible to be an alchemist without being an herbalist but is not recommended.
Potions are created from herbs. You will also need to buy various reagents from the Profession merchants as well as find rare reagents from monsters, fishing, chests, or other players.

Getting new Recipes
The Alchemy trainer will teach you many recipes. Additional recipes will have to be found from monster drops, chests, or (more commonly) purchased from other players. You can unlock additional recipes with reputations. Make sure you tell your friends you are an Alchemist and they may bring you recipes and reagents.

Alchemy for Profit
You can sell potions to other players. Build a stack of potions then figure out a good price for them. You may have to experiment with the prices until you reach the right price. Inform players about the benefits of your potions and why they should want to buy them. Some potions will be more popular than others. Everyone likes healing potions! Sell your potions in the auction house.