A ranged attack is an attack that can hit a target who is more than one square away. Ranged attacks will not trigger many of the passive attacks that are triggered by melee, even if the target is within melee range.
Some examples of ranged attacks are:
- Anything that is thrown, especially missile weapons (darts, arrows, etc.)
- Attack wands, notably striking, cold, fire, and lightning
- Most attack spells, such as force bolt
- Monster breath, such as a dragon's
Ranged attacks should be preferred to melee for their ability to damage enemies before they can damage you. Even classes that are more skilled in melee attacks will benefit from carrying around some kind of ranged attack, if for no other reason than to avoid the passive attacks of jellies, rust monsters, and their ilk.