Immigration is the movement of people to a non-native country where they do not have citizenship, in order to settle as permanent residents or naturalized citizens. Travelers, tourists, and other short-term stays in a destination country do not fall under this definition. Seasonal labor migrants are sometimes called immigrants. Research suggests that migration is economically beneficial for both receiving and sending countries. The process of immigration also has social and cultural benefit to the countries. Immigrants face various challenges including discrimination in criminal justice, business, economy, housing, health care, media and politics. Different approaches, evaluations, methodologies and advanced studies on immigrants have been included in this book. Such selected concepts that redefine ideas on immigration are presented herein. A number of latest researches have also been included in this book to keep the readers up-to-date with the challenges and concerns related to immigrants.