Forehead Protector

The forehead protector, or hitai-ate, is the bandanna that is worn by every ninja, composed of a metal plate engraved with the symbol of the ninja's Hidden Village and a strip of blue cloth. The forehead portector is received once you graduate from the Ninja Academy, so Genin ninja and up are only seen with it. Despite the name 'forehead protector', they can be worn in many different ways. For example, while the majority do wear theirs in the traditional manner, Sakura uses hers as a barrette, and both Temari and Hinata wear theirs around their necks. The bandanna part of the forehead protector itself is clearly optional, since Kankuro's is sewn onto his hat instead. Rock Lee and Ino both wear theirs as belts, and Gaara keeps his tied onto the strap of his sand gourd and almost entirely out of sight. Since the forehead protector is meant to symbolise pride in fighting for one's home village, this is probably because during the Chunin Exams arc he fights only for himself, or from a design point of view, because it would cover up his deep and meaningful forehead kanji.

A missing-nin does not stop wearing their forehead protector, but they do make a long horizontal scratch across the symbol to show off their rejection of their home village.