Here is a model for a partnership oath that is widespread in many countries: the twinning of cities begins for many reasons. In general, twin cities have similar demographics and sizes. They can be created from business links, travel, similar industries, diaspora communities or common history. This is how the partnership between Portland, Oregon and Bologna, Italy, was born of common industries in the field of biotechnology and education and a “similar attitude towards food”, while Chicago`s link with Warsaw, Poland, with the historic Polish community of Chicago began.  The twinning between Indianapolis and Monza, Italy, is due to the long connection between the two cities and motor racing. Although the term is often used interchangeably, with the term “friendship city,” this may mean a relationship with a more limited scope in relation to a partner city relationship, and friendship city relations are mayors-mayors of the agreements.  America, South Asia and Australasia use the term “twin cities” or “twin cities.” In China, it is the term “Yuh`o chengshe”, friendly cities.  Sometimes other government agencies include a partnership relationship, such as the agreement between Hainan provinces in China and Jeju-do in South Korea. The twelve is a twinning of cities with a city from each of the Member States of the European Union.   Among the cultural events in the twin city is the annual National Cherry Blossom Festival in Washington, D.C. Many twin cities have trade agreements with their partners. For example, the Vermont Glacier opened a plant in the Republic of Karelia in Russia and offered its Russian employees the same profit-sharing plan.
The twinning of cities is not a new concept for human society. For years, there have been partnerships that date back to Europe in the second century. These links were limited to cities and municipalities (local authorities) in the early years. Since then, links have been established between schools, churches, libraries, port authorities, airports, radio and television stations, postal services and other local authorities, and charities, regional, regional and provincial governments. Twinning agreements are legal or social agreements between two cities to promote trade and tourism.