Human migration is driven by both "push" and "pull" factors. Key "push" factors include poverty, political oppression, armed conflicts, and poor environmental conditions in places of origin. Important "pull" factors are perceived economic opportunities, family/social connections, and improved quality of life in destination locations. Migration can take place internally within a country or internationally across borders. Both voluntary and forced migration streams have significant impacts on societies and challenge policymakers to respond to humanitarian crises.