Experience points can be gained either by finishing achievements and quests or by defeating monsters. Experience points will make your character advance levels and your character's basic attributes will also advance.
As you level up, your health and mana levels will also increase, so your character will have more magic and damage capacity.
Experience Table
Currently all new characters start at level 1 being the maximum level that can be reached today at level 101.
The current levels will not be reset but the experience/lvl calculation system could be modified. Experience Points will not be reset anywhere
Player earning experience points after killing a Goblin