Sturdy as Mountains
Dwarves are a squat, stout people. They rarely reach five feet in height, but can weigh as much as a grown human who stands nearly two feet taller. Their constitution is practically legendary and some people actually believe dwarves are immune to any poison (this is absolutely not true). Their hair, skin, and eye coloration fall in the same range as humans, though they tend towards earthy colors. Both male and female dwarves grow beards and braid all their hair into intricate designs. Dwarves can live up to 400 years, making them the second longest living race after elves.
Proud but Reliant
Dwarves cannot afford to be xenophobic, but that does not mean they are entirely trusting, either. Underground agriculture being unreliable at best, these stout mountain dwellers rely on topsiders for much of their foodstuffs. Usually, they trade with halflings, who seem to have a knack for farming and pastoralism, but dwarves will trade for food with anyone. This reliance can create awkward, strained relationships with surface dwellers, though. Aside from tieflings (whom few trust), dwarves probably take the greatest issue with orcs, because the latter rarely carries traditional currency and refuses that of the former.
Riches of the Earth
The greatest jewelers, smiths, and stone carvers in the world are probably dwarves. Their lives depend on it, and so their whole culture revolves around it. They have relatively easy access to the various precious minerals, metals, and gemstones the earth has to offer. Since these materials are sometimes used as currency by most of the other races, dwarves often mint the currency in their geographic and political region. Crafters and smiths hold the most wealth and status in dwarven society, followed closely by the miners and alchemists who pull the raw material from the earth and then refine it. Merchants are a unique class, spending significant portions of their lives above ground and dealing with the other races the most. They are considered the lifeblood of all dwarven settlements, responsible for bringing all the goods necessary for keeping a society functioning back to the mountain holds. As such, dwarven merchants are shrewd folk. They need the foodstuffs and other useful materials from the surface dwelling races, but those races rely heavily on dwarven industry, as well. And dwarves are never shy about reminding them. So, when a dwarven merchant sets a price, they (almost certainly) never budge on it.