From a purely educationist perspective, gaining a deeper understanding of several aspects related to the prevalence of autism/ASD in a given population is of great value in planning and improving educational and psychological intervention for treatment, training, and teaching of children with this disorder. In this article, I present and discuss numerous facets of prevalence studies, beginning with assessing the changes in diagnostic manuals (DSM and ICD) over time. Based on the existing available research literature and empirical studies published during 2000 to 2016, I address the geographical-dimension and age-dimension of prevalence of autism/ASD. Over 50 studies from 21 countries reveals that prevalence rates of autism/ASD among children are on rise. There are inter-national and intra-national, regional/territorial variations with regard to prevalence rates, and I present and discuss possible factors/factor-groups that can explain these variations. Regardless of their geographic location, children with autism/ASD can be treated, trained, and taught, but to do so effectively requires reliable prevalence studies that can properly inform policy makers and higher institutions about the steps that must be taken in the field in order to improve the learning conditions of these children with special needs. Moving forward, it's essential that studies of geographical dimension and age dimension of prevalence of autism/ASD must be supplemented by other (i.e. gender, socio-economic, ethnic, cultural, and language) dimensions to help give us the perspective we need to grapple with this increasingly common disorder.