There are a huge number of displayable titles that can be earned in Forsaken World. Titles can be earned for everything from completing certain quests, performing well in events, killing powerful bosses, and a vast array of other tasks. Titles are color coded according to the difficulty of gaining them. Grey titles are the easiest, while purple titles are the most difficult to achieve.
You can view all of the titles you've gained by opening your character screen ("C" key). Open the tab in the lower left called "Titles", and you'll see a list of all of the titles you've earned. To display a title, just click the "Set Title" button near the bottom of the window. You can change your displayed title whenever you want.