A wide range of factors is responsible for the migration of the population. Based on the effect which is causing such migration, it can be categorised as favourable and unfavourable factors. The favourable factors (positive factors, i.e. work or economic opportunities, to join family, or to study) that attract people towards a location are called pull factors.
The unfavourable factors (negative factors, i.e. to escape conflict, persecution, terrorism, or human rights violations) which make the people move out from a location are called push factors. The movement in response to the adverse effects of climate change, natural disasters, or other environmental factors are also categorised as push factors. The various causes which are responsible for human migration are categorised under five groups as follows.