Yes, Gibraltar citizens are also British citizens. Gibraltar is a British Overseas Territory located on the southern tip of the Iberian Peninsula, and its citizens are considered British citizens under the British Nationality Act 1981.

Gibraltar's status as a British Overseas Territory means that it is under the sovereignty of the United Kingdom but has its own government and is largely self-governing. As a result, Gibraltar citizens are entitled to all the rights and privileges of British citizenship.

For example, Gibraltar citizens can hold a British passport, which allows them to travel freely within the European Union and access consular assistance from British embassies and consulates worldwide. They also have the right to live and work in the United Kingdom without any restrictions.

It's worth noting that Gibraltar's status as a British Overseas Territory has been a subject of dispute between the United Kingdom and Spain. However, the British government has consistently affirmed Gibraltar's British status and the citizenship rights of its residents.

References:

1. Government of Gibraltar. "Gibraltar Nationality." https://www.gibraltar.gov.gi/new/born-in-gibraltar
2. UK Government. "British Overseas Territories." https://www.gov.uk/guidance/british-overseas-territories-citizenship