Unity in diversity is used as an expression of harmony and unity between dissimilar individuals or groups. It is a concept of "unity without uniformity and diversity without fragmentation" that shifts focus from unity based on a mere tolerance of physical, cultural, linguistic, social, religious, political, ideological and/or psychological differences towards a more complex unity based on an understanding that difference enriches human interactions. The idea and related phrase is very old and dates back to ancient times in both Western and Eastern Old World cultures. It has applications in many fields, including ecology, cosmology, philosophy, religion and politics.

Multiculturalism in Canada was officially adopted by the government during the 1970s and 1980s. The Canadian federal government has been described as the instigator of multiculturalism as an ideology because of its public emphasis on the social importance of immigration. The 1960s Royal Commission on Bilingualism and Biculturalism is often referred to as the origin of modern political awareness of multiculturalism, resulting in Canada being one of the most multicultural nations in the world. The official state policy of multiculturalism is often cited as one of Canada's significant accomplishments, and a key distinguishing element of Canadian identity and Canadian values.