ABSTRACT
During the second half of the last century, urban population increased tremendously. While during the 1950s urban residents did not exceeded 200 million, at the end of the century their total number was close to 3 billion and it is expected to increase to about 9.2 billion by 2050 (UNFPA, 2006). Transfer of people to cities has mainly happened and will continue to happen in the so-called less developed countries as the result of increased economic and social opportunities offered in urban areas and the degradation of rural economies and societies.
