Giraffe horns are not actually called horns but ossicones and both female and male giraffe have them. Ossicones are formed from ossified cartilage and are covered in skin.
Giraffe are born with their ossicones, however, they lie flat and are not attached to the skull to avoid injury at birth. They only fuse with the skull later in life.
Both female and male giraffe have a main pair of ossicones. While female ossicones are often thin and tufted, male giraffe normally have thicker ossicones that become bald on top as a result of frequent necking. In some species males grow a second pair of ossicones behind the first pair, as well as prominent ossicone in front of the main pair. This median (middle) ossicone of the male adult Northern and Reticulated giraffe are on average considerably larger than those of the Masai and Southern giraffe – a key morphological feature which further divides giraffe into different species.
Ossifications on the head of male giraffe add weight, which often increases with age enabling them to deliver ever heavier blows during necking contests. Fatal combat is rare but does occur.