Professions, formerly known as Trade Skills are non-combat jobs that your character can take on which lets them craft weapons and items, or improve them. Your character may have up to 2 professions, and any number of secondary skills (lesser professions). Complete and updates profession guides can be found at Skryer.

Professions have different level requirements which require you to be higher in level to advance, so that you can't just craft all day along to become good. There are 3 types of professions:

Gathering Professions - These are the raw material skills that are needed in order to craft items, some may find these useful just to trading, and some may use these to gather resources for their own crafting.

Herbalism

Mining

Skinning
Production Professions - These jobs enable you to create and enhance items which are cheaper and more powerful than the ones sold at vendors. A lot of good items can be bought and sold from crafters.

Alchemy

Blacksmithing

Enchanting

Engineering

Leatherworking

Tailoring
Secondary Skills - Anyone can learn all of these as these only allow minor enhancements which benefit players in small ways.

With the release of World of Warcraft: The Burning Crusade, many core aspects of the game will be improved, expanding the choices available to players and streamlining some gameplay elements. For example, new raid encounters are being designed for a maximum of 25 players, and the PvP system will change how honor works in the game. Following this general strategy of making gameplay even more rewarding and expanding the playing experience with new, interesting content, the professions of World of Warcraft are also set to receive major updates to ensure that they remain a fun and worthwhile part of your adventures in Azeroth and beyond.
When the time came to begin the professions update for the expansion, the dev team took a very close look at all the work that had gone into the profession system so far. There were some things the team felt could be improved in World of Warcraft's professions to make them more interesting, more valid, and most importantly, even more fun. The expansion will allow the dev team to upgrade the profession system, and to provide players with cool new gadgets, equipment, and consumables that will help them brave the many challenges of Outland.

On the following pages, you'll find a brief summary of what changes you can expect to see in World of Warcraft: The Burning Crusade for each profession. Keep in mind that there is always a chance that these plans may change, but this is what's on the drawing board at the moment.