Your character has a set of base attributes that are automatically increased when you gain new levels. Attributes have a direct impact on your character's abilities and powers.
Here are some of the most important attributes:
•    Strength: Gives you a damage bonus for melee attacks and also increases the attack rating for certain weapons.
•    Dexterity: Gives you a bonus to your defense rating and increases the attack rating for certain weapons.
•    Constitution: Determines the amount of health and stamina your character has.
•    Intelligence: Determines the amount of mana your character has, and increases magic rating for mages.
•    Wisdom: Determines the amount of mana your character has, and increases the magic rating for priests.
Ratings and resistances
These numbers basically affect your character's powers in attacking, defending, use of magic and more. They are altered by your attributes and possibly even what equipment you use.
Skills
Depending on your character's class you have a set of skills that are either working in the background while you play, or you will have to activate them yourself by using various abilities. When you gain a level you may also gain a set of points you can invest in these skills to make them more potent. You invest skill points through the character window.
Here are some of the most important skills:
•    Perception: Determines how well you observe the environment around you. May allow you to spot hidden enemies or even dangerous traps.
•    Bandaging: Allows you to quickly heal outside combat. A better skill may heal you faster.
•    Renew mana: This is similar to bandaging, but instead it affects your mana pool.
•    Concentration: Determines how prone you are to having your spell canceled if distracted.
•    Hiding: This skill allows you to hide and become invisible to others. A higher skill allows you to hide better and become more difficult to spot.
•    Climbing: Determines the difficulty of objects (such as ladders) and slopes that you can climb. You may climb by using climbing spots in certain areas.
•    Taunt: The higher your skill in taunting, the greater chance of making enemies aggressive towards you. The maximum number of points you can invest in a skill increases as you gain new levels.