Traits

Every character has several traits. Some are game defining and a few come into play at rare occasions. The rare ones are your choices of alignment.

Class
Every Character has a Class. A class defines what special things a character can do. Basically it is a set of abilities that you gain in a certain order. A character can have more then one class, if that is the case the character is a multi-class character. Multi-class characters are usually broader in ability, but lack the specialization of a Single-class character. Multi-classing can be a tricky thing, so there is an extra rules section on Multi-Classing.

Character Level
A characters Level defines what abilities a character has. The most notable feature related to Level is the number of Hit Dice and therefor Hit Points a character has. Character Level and number of Hit Dice are interchangeable terms.

If you are playing a PC using one of the standard species the following formula holds true:

ECL = Character Level = Sum of Class Levels

Racial Hit Dice (racial HD)
However some species might come packed with racial hit dice. This means that because you play a member of such a species, you start out stronger and therefor are somewhat limited in the number of Class Levels in the end.

If you are playing a PC using a race that has more then one racial hit dice (the first one is substituted by the hit die your class grants) then this formula holds true

ECL = Character Level = SUM of Class Levels + Number or racial HD

Effective Character Level (ECL)
Further some species might have potent magical or supernatural abilities. In that case they have something called Level Adjustment. This number increases your Character Level like having extra Hit Dice, but you don't get them because those features are so strong. Because this is a little bit different to Hit Dice and Levels you have an Effective Character Level that is bigger then your character level.

If you are playing a PC using a race that has both racial hit dice and a level adjustment, then this formula holds true:

ECL = SUM of Class Levels + Number or racial HD + Level Adjustment

Of course the formulas above equate to this one because your normal racial HD is substituted by your class' HD and your LA is 0.

Size Category
Every creature falls into a size category. To be precise even vehicles and buildings fall into these categories. And as long as your level does not reach a critical number, most of the stuff will be in a range you experience when take a walk in the streets.

Ability Scores
Every character has six ability scores. These have a positive value (starting from 1 and no upper limit). It is assumed that a score of 10 is average human ability with a normal range from 8 to 12, where the higher the number the better that attribute is.

Remember that all changes are retroactive. Losing points in Constitution has the additional drawback of losing HP at the same time. This makes poisons that cause Constitution damage very dangerous. If a magical effect reduces your Intelligence score for a short time you do not lose a skill, but if it becomes longer than the duration of a fight mark one skill as untrained for that time.

Strength
Strength measures your character’s muscle and physical power. This ability is especially important for fighters, barbarians, paladins, rangers, and monks because it helps them prevail in combat. Strength also limits the amount of equipment your character can carry.

You apply your character’s Strength modifier to:
 * Melee attack rolls;
 * All Weapon damage rolls except for crossbows;
 * no matter how strong your penalty you'll always do 1 point of damage;
 * For Bows you normally only apply penalties, but "composite" bows allow to add your Bonus as well;
 * The sports skill has Strength as its key ability;
 * Strength Checks for breaking doors or bending bars.

Dexterity
Dexterity measures hand-eye coordination, agility, reflexes, and balance. This ability is the most important one for rogues, but it’s also high on the list for characters who typically wear light or medium armor (rangers and barbarians) or no armor at all (monks, wizards, and sorcerers), and for anyone who wants to be a skilled archer.

You apply your character’s Dexterity modifier to:
 * Ranged attack rolls including thrown weapons;
 * Armor Class (AC);
 * If you have a bonus and can react to an attack your bonus applies;
 * If you have a penalty, it always applies;
 * Evasion safes to escape area attacks (such as falling rocks or fireballs);
 * Most physical skills have Dexterity as key ability.

Constitution
Constitution represents your character’s health and stamina. A Constitution bonus increases a character’s hit points, so the ability is important for all classes. Some creatures (such as undead) or Constructs don't have a Constitution Score.

You apply your character’s Constitution modifier to:
 * Depending on your Constitution Modifier you get more or less HP per level (but always gain at least 1 HP/level) equal to your Con modifier. So if you have a bonus of +1 you get one additional HP per level;
 * Affects two saving throws;
 * Poison or Death to overcome lethal poisons and dangerous powerful magic;
 * Endurance to overcome harsh physical activities like forces march without suffering.

Intelligence
Intelligence determines how well your character learns and reasons. This ability is important for wizards because it affects how many spells they can cast, how hard their spells are to resist, and how powerful their spells can be. It’s also important for any character who wants to have a wide assortment of skills. Mindless creatures do not have a Intelligence score and a score of 3 or higher reflects human like intelligence.

You apply your character’s Intelligence modifier to:
 * If you have an Intelligence Bonus when creating a 1st level character, you get additional foreign languages;
 * If you have an Intelligence Bonus you train additional skills to the same amount as your Intelligence Bonus;
 * Your Intelligence Modifier applies to Logic and Disbelieve saves to overcome Illusions and to prevent buying your own buildings multiple times;
 * All knowledge Skills and a few mental skills rely on your Intelligence Score;
 * If your character has a Profession you may choose to go the intellectual way towards your profession;
 * Intelligence is a spell-casting attribute.

Wisdom
Wisdom describes a character’s common sense, perception, and intuition. While Intelligence represents one’s ability to analyze information, Wisdom represents being in tune with and aware of one’s surroundings. Wisdom is the most important ability for clerics and druids, and it is also important for paladins and rangers. If you want your character to have acute senses, put a high score in Wisdom. Every creature has a Wisdom score. You apply your character’s Wisdom modifier to:
 * Insight saving throws to resist temptations and the effects of charm spells;
 * Several skills that rely on experience through practice use Wisdom as their key ability;
 * Wisdom is a spellcasting attribute.

Charisma
Charisma measures a character’s force of personality, persuasiveness, personal magnetism, ability to lead, and physical attractiveness. This ability represents actual strength of personality, not merely how one is perceived by others in a social setting. Charisma is most important for paladins, sorcerers, and bards. It is also important for clerics, since it affects their ability to turn undead. Every creature has a Charisma score.

You apply your character’s Charisma modifier to:
 * Will Saving throws are based of Charisma and are often used to resist fear effects;
 * All social Skills use Charisma as key ability;
 * Turning Undead and some other paladin abilities rely on Charisma to boost their power;
 * Charisma is a spellcasting attribute.

Ability Modifiers
All Ability scores are associated with a modifier. Also Spellcasters get bonus spells if their Spellcasting Attribute is exceptionally high.