Arrows were projectiles that were fired from bows. They had sharp, triangular points at one end, a wooden shaft in the middle, feathers on the end of them as well as a nock (a notch on the back of the arrow to hold the bowstring). To fire one of these projectiles, a person had to nock an arrow onto the piece of thin string connecting the two ends of the bow. Once nocked, the user of the bow had merely to pull back on the string and release his fingers to allow the arrow to soar through the air, hopefully to find its target.
Uses for arrows
Arrows were used to take out distant enemies. In a normal battle, archers (people or soldiers who use bows and arrows) would be behind foots soldiers and other infantry, so as to be protected. These archers would fire their arrows into the enemies behind the front line so that the reinforcements of the enemy would eventually be wiped out.
Users of arrows
Since nearly every race uses bows, the same applies to arrows. Elves, humans, dwarves, and even Urgals wield the bow and arrow. The different strengths, weaknesses, and attributes of these unique races lead to different ways bows and arrows were used and the effectiveness of these two weapons. Eragon uses a bow and arrow on many occasions, including the murders at Yazuac (where he also first used magic) and during his hunting of a deer right before he discovers the blue "stone". The Ra'zac or Imperial soldiers might use arrows, as one was deflected by Roran as he fought with both.
What were arrows made of?
Most bows and arrows were made of wood, with the exception being the Dwarves, who made their bows using Feldûnost or Urgal horns for greater support for the archer (since even an archer could not be completely still). The point at the end of the arrow was made of either iron or, if the race was primitive enough, stone. The end part of the arrow was made of feathers for aerodynamic reasons. In Brisingr arrows from Galbatorix's archers were enchanted to be able to penetrate wards and the like.