Increasing ability scoresEdit
All characters gain a permanent +1 increase to a chosen ability score at 4th level and every 4 levels thereafter (4, 8, 12, etc.). At level 20, the character will have gained +5 ability points this way.
This increase can be used on any of a character's ability scores and is not restricted based on that character's previous choices.
For example, a rogue increases his dexterity from 16 to 17 at 4th level. When he reaches level 8, he can further increase his dexterity to 18 or may choose to increase any of the other 5 abilities instead.
In addition to this progression, characters may also gain ability score increases from other sources such as class features (e.g. barbarian rage), class feats (e.g red dragon disciple), epic feats (e.g. great strength) or spells (e.g. bull's strength).