What are examples of economic, social, political, and environmental impacts of the immigration of people on a host country?

Economic - most economists agree that immigration represents a net positive for the economy of a country, mainly because they represent a shift to the right of the Aggregate Demand curve.

Social - immigration can result in many social changes. It can help develop new cultures through cultural diffusion, or it can raise social tensions due to cultural differences.

Political - Immigrants can become a voting block for a particular political party of politician, and this can upset the political climate.

Enviromental - immigration increases population and population density, and these two things result in more pressure on the enviroment.