I'm building a mobile application, specifically a signup page. Due to the data driven nature of the app we ask users to enter their ethnicity. Perhaps this is not the right place to ask this, but what is the standard list/selection method? I'm looking for advice on single vs multi-select and a suggested comprehensive list of ethnicities so nobody is left out. I've looked at various other websites but either this field isn't present, and where it is the list is different.

Please retag or move as appropriate, though hopefully this is at home here.