Urbanization is the process of human migration from rural areas to cities, therefore rapid urbanization means that the speed at which migration from rural to urban areas occurs is hastened compared to that of a country there is no time to plan their existence in cities. The situation differs from country to country as the number of cities and rural areas in the countries is different. Another possible reason for the difference is the developmental nature of the countries; some countries are developed, some are developing while others are considered less developed. Urbanization in developed areas can be traced back to the era of industrialization, when people migrated from rural/ancestral homes to cities in search of work. According to a report compiled by the University of Michigan, the percentage of the global human population living in cities in In 1950 was less than 30%, and in 2000 the figure was 47%. The study predicted that by 2025 the percentage would reach 60% (World watch, 2011). Rapid migration is the result of factors that induce migration from rural to urban areas; these factors have been classified into two large groups: push factors and pull factors. Push factors are those factors that are influenced by conditions in rural areas and that push people to move to cities. Pull factors, on the other hand, are the incentives that attract people to cities. Examples of push factors include political instability in rural areas, insecurity, low levels of education, unemployment and scarcity of resources. Pull factors are the promise of what is missing in rural areas: employment, better education, better lifestyle, variety of resources, better healthcare facilities and some political stability... middle of paper... Urbanization and megacities: the need for spatial information management.' FIG REPORT publication n. 48, January 2010. Retrieved March 9, 2011, from www.fig.net/pub/figpub/pub48/figpub48.pdf*University of Michigan, 'Urbanization and Global Change', April 1, 2006. Retrieved March 9, 2011, from http: //www.globalchange.umich.edu/globalchange2/current/lectures/urban_gc/*WORLDWATCH INSTITUTE. "Rapid urbanization catches experts' attention." Vision for a Sustainable World, March 9, 2011. Retrieved March 9, 2011, from http://www.worldwatch.org/node/64*Zhou, Hongjian, et al. “Rapid Urbanization and Implications for Restoring River Ecological Services: Case Study in Shenzhen, China.” Journal of Urban Planning and Development: 10.1061. Retrieved March 9, 2011, from http://ascelibrary.org/upo/resource/3/jupdxx/33