Dark and Light/Stats
All information stated here is based on 0.88.81 and may (hopefully!) be subject to change as the game progresses.
Strength influences the melee damage a character can inflict with a basic (read: non-skill) attack. It also governs the maximum weight a character can carry.
Constitution governs the maximum Hit Points and Stamina Points of your character and, to some extent, your resistances. That makes it one of the most crucial stats for Fighters and Hunters. This stat may also affect how long your character can last in a coma state waiting for a healer to revive you.
High Dexterity improves the chance-to-hit for basic attacks. Whether or not it has an influence on skill-based attacks, parrying for instance, is not yet entirely certain.
Quickness hastens basic attacks (and thus probably also the rate at which skill based attacks can be used as long as they are not blocked due to cooldown). It also governs the character's chance of evading (only?) basic attacks.
As of 0.88.81, a high QUI value makes the character virtually untouchable with basic attacks. Because this leads to massive PvE imbalance in favor of casters with AoE Damage spells, it will propably be toned down in the future.
Intelligence determines the maximum Mana Points of your character, and also determines the power of spells for the Mage classes. It may also be important for other casting classes like Clerics. It may also contribute to passive combat skills for melee characters.
Wisdom determines how spiritual your character is and is therefore important to Clerics and other classes that rely on a connection with their God to determine the power or their spells. High Wisdom can increase divine protection and resistances to divine diseases. Tactically, this governs the character's ability to regenerate mana points. It was meant to be "to the healer what intelligence is to the caster", but as of now it is not certain exactly how this is the case.
Charisma determines the physical and social attractiveness of your character. NPCs will interact with you differently depending on your charisma. Some NPCs may not want to interact with you at all if your score in this stat is too low. Thus, advancing in the political sphere may make this stat of paramount importance to your character.
In addition to the 7 basic stats for each character, your class may offer abilities that affect your resistances: These stats refer to a characters ability to resist damage or effects of various types such as heat, cold, poison, disease, and magic. A character that focuses on bolstering their heat resistance would have much less to fear from a fireball being tossed their way. However a character lacking any fire resistance could expect to become charbroiled.