Each character in DR has eight attributes associated with them, which are initially chosen at character creation time through random rolls. After these initial attributes are set, you can add to each of them through the use of TDPs, which is also discussed here.

Strength is used to determine a number of things in game, most notably maximum burden, damage, and weapon round times. In the case of burden, strength is the primary factor, with stamina and discipline also playing a part in determining the maximum you can carry for each stage of burden. Strength's role in damage and round time are generally balanced with agility and are heavily weapon dependent, but the general rule is that the more strength you have, the more damage potential. It also plays a part in some physical activities, such as swimming and dragging.

Reflexes are mostly helpful as a bonus to combat skills, in particular: Evasion, Parry, Shield, and Multi Opponent. For most guilds, there aren't a lot of other practical uses for the attribute.

Agility plays a large role in determining damage and hit average while hunting. The higher the agility, the more likely you are to strike a target. (Of course weapon ranks are more important.) Agility is also helps with the targeted magic, skinning and disarming skills. There seem to be a number of other places where agility plays a factor, though it's not obvious just how much, such as in shifting.

Charisma's an often neglected attribute, and for quite a while deservedly so. Now, charisma does help in a number of practical ways, such as increasing your spirit help, which directly increase the amount of time it takes before you auto-depart. Supposedly it also helps in a number of magical spells, but it would seem it mostly impacts PvP situations. Additionally, you can barter for lower prices with shopkeepers and there are rumors that it increase critter box drop rates. For Traders, the spell has the added benefit of helping with the values you get for selling gem pouches. Empaths will find that this also helps in shifting.

Discipline helps in the learning process by prolonging the length of time you can learn before your overall mindstate worsens. It also plays a small part in increasing your learning pool size and is used in very small part to determine burden.

Wisdom and intelligence really only have practical applications in learning, though there are some small gains in spellcasting.

Stamina is the driving attribute behind how much total damage you can take. It's directly responsible for your 'hit points.' (For lack of a better term.) It's also a large factor in determining burden and how long before you become fatigued in things like combat and swimming. There also seems to be a direct correlation between your stamina and the ability to fight off disease and infections.

Concentration is used to determine how long you can concentrate on certain tasks, most notably thief Khris and magic. Runestones in particular seem to use concentration, which can be noticeable at low levels. Concentration is determined as:

(discipline * 3) + (intelligence * 1.5) + stamina

TDPs, or Time Development Points, are used to increase attributes. The play.net site shows that the formula for figuring out the cost of raising an attribute is:

(current attribute x 3) + (racial TDP cost x current attribute / 2)

The Racial TDP cost being anything from -3 to +3 (with -3 being easier to train.)

TDP accrual is somewhat less than obvious, however. Each character basically has a pool that needs to be filled up in order to gain a TDP. This pool keeps track of every rank that you gain in a skill and adds that number into it. For instance, if you just got your 50th rank in skinning (and assuming your pool was completely empty) you would now have 50 points in this pool. Every time this pool reaches 200, you gain one TDP. The pool does not reset, so if you were to gain 110 in foraging and 110 in swimming, you would now have one tdp and 20 points in the pool. There is no way to check this pool in game and is not considered knowledge a character would ever have.

You also gain TDPs each circle, though how many you gain is to some degree, still a small mystery. It would seem there is a point at which you stop gaining 50 + circle TDPs and start to gain 100 + circle TDPs.