Achievements are tracked per account
There are over 300 achievements in the game, ranging from PvE, Roleplaying, Crafting, Exploration and PvP.
Upon a completed achievement you may receive gold, skillscrolls, rare items, titles, or just some fireworks. All depending on difficulty.
Your personal achievements tracker is accessed through the character paperdoll by clicking on the "quest" button. It will pull up a gump, allowing access to a multitude of features.

Daily Achievements are now available with great prices

Achievement Menu

Achievements highlighted yellow indicated that you can receive a reward. Click on the green circle. Every achievement has a reward.