What is a sister city?

A “sister city” agreement, also known as a “twin city / town” (commonly used in Europe and the UK), is a long-term partnership between two cities that is usually based on a formal memorandum of understanding reached by the designated official from both communities. 

The initial purpose of twinning was to reconcile diplomatic relationships after World War II. Modern twinning has been further enriched by the emphasis on economic, education, and environmental partnerships.

“Sistering” or “twinning” arrangement is a form of “city diplomacy”, referring to the engagement in international relations of local government with other political communities and non-governmental bodies. 

The political meaning of sister city and detwinning:

Twinning as a type of “city diplomacy” is sometimes used for political purposes. For instance, the signing of a twinning agreement can be used to acknowledge the status of a politically disputed territory. The termination of sister city agreements, or detwinning, is also deployed as a strategy to convey political messages.