The Gibraltar identity card is an official identity document issued by the Government of Gibraltar to all British citizens living in Gibraltar, which also serves as a valid travel document within the European Economic Area and Switzerland for holders who are British Citizens or British Overseas Territories Citizens connected to Gibraltar.
On a unilateral basis, Gibraltarians are permitted to use their identity cards (instead of their passports) to enter Albania, Bosnia and Herzegovina, and Serbia.
References
Gibraltar identity card Wikipedia(Text) CC BY-SA