A migrant crisis occurs when large numbers of immigrants—including refugees, asylum seekers, or displaced persons—move into a destination country, often overwhelming its systems and communities. These movements are typically triggered by unrest, economic hardship, or political instability in the migrants' countries of origin. The sudden influx of people often strains public services, infrastructure, and social cohesion, placing undue pressure on citizens and local governments. These situations can also raise humanitarian concerns, as existing facilities are rarely equipped to handle large numbers effectively. Notable examples include the European migrant crisis, the English Channel migrant crossings, and post-World War II displacements.
A refugee crisis refers to a movement of "large" groups of displaced people, and may or may not involve a migrant crisis. Compared to refugee crisis (refugee is a refugee), migrant crises also have a separate or distinguish between the "deserving" refugee from the "undeserving" migrant and play into fear of cultural, religious, and ethnic difference in the midst of increasing intense, excessive, and persistent worry and fear about everyday situations and lacking in predictability, job security, material or psychological welfare for many in Europe (such in closure of Green Borders).