Attack Range

Attack Range refers to the range at which a Hero may use his or her basic attack ability on another unit. There are two main subdivisions of attack range: melee and ranged heroes. Attack range cannot be extended except by certain abilities.

Melee Heroes
Melee Heroes have very little range, and must be close to enemies in order to attack them. Typically, Melee Heroes have Strength as their Main Attribute, as it allows them to tank damage easily, though there are exceptions.

Mechanics
Melee Heroes usually have an attack range of 128 units (although Doom Bringer has a range of 150 units, and Tiny with an Aghanim's Scepter has a range of 235). They earn a base of 36 Experience when a nearby unit is Denied, as opposed to a Ranged Hero, which only earn 18. Melee Heroes also receive greater benefit from certain items, such as Vanguard or Quelling Blade. Additionally, some abilities only affect Melee Heroes, such as Skeleton King's Vampiric Aura or Vladmir's Offering's lifesteal aura.

Cleave
Melee Heroes can use Cleave, which deals damage over an area around them on each attack. The damage from Cleave is determined from the attacking unit's damage, reduced by a percentage, and delivered to all enemies in the radius. It is not affected by armor value, only armor type. Cleave does not work for Ranged Heroes.

Ranged Heroes
Ranged heroes have the ability to attack enemy heroes from a distance. Ranged heroes can have a variety of differing attack ranges, from little more than a melee hero to over 600 units. Ranged heroes also benefit from certain auras, such as Drow Ranger's Trueshot Aura. However, they also receive a lower benefit from many items, such as Vanguard or Skull Basher and cannot receive any sources of cleave or lifesteal auras, due to the advantage their range gives them in attacking enemy heroes or creeps.

Ranged heroes also have a 25% chance to miss any unit they attack when firing uphill.