The meaning of immigration.

(1) Persons who have moved to other places for permanent residence;

(2) A large number of organized population movements.

(The above definition comes from Cihai)

Move to another country to live, work, study and live.

Immigrants are legal permanent residents. Permanent residents enjoy roughly the same rights as American citizens. For example, they can live in the United States indefinitely, work in the United States, and freely enter and leave the United States.