It may occur within a country or it may require crossing an international border. It may be short term/temporary or long term/permanent. Based on the area of origin and destination, this migration can also be classified as: rural-rural migration, rural-urban migration, urban-rural migration, or urban-urban migration. Although there is no consensus on how long the period should be for defining this type of migration, a range of 3-12 months is frequently found in the literature.