The site uses OnoMap, an academic project developed at University College, London. Consideration of language, religion, geographical region and culture in relation to names has resulted in 185 Categories organised into 66 Subgroups and 16 Groups. So what do these reveal for our clan? I put 'McIlhagga', 'McIlhagger' and 'McIlhaga' in to the site 'search term' box. First a World Map appears and then you can click on a country to get a more detailed map of an Area, like Europe. Then you can click on a Region, e.g. Ireland, to give even more detail. Each map is coloured in six shades to show from high to low density of a name. These maps are of course showing present day usage of a name, not historical usage, so are different from maps produced from historical sources, such as censuses. Tables with statistics and names give the top five Countries, Regions and Cities, and the top five forenames associated with the surname.
Finally under the title 'Roots of this name' you are given 'Group', 'Subgroup' and 'Language'. There is also a question for you to respond to, 'Do you agree? Yes/No'. For McIlhagga we are given, Group: Celtic; Subgroup: Scottish; Language: English. For McIlhagger we have Group: Celtic; Subgroup: Irish; Language: English. For McIlhaga we get the message 'Sorry we don't have any information on the roots of this name'. For McIlhagga and McIlhagger I ticked 'Yes, I agree'.