Basically, and briefly, you search for a surname and Pubic Profiler/World Names shows you the countries where your surname will be found and something they call "FPM". To quote the site: "We always use the relative frequency of a name compared to the overall population in an area. This is expressed as a 'Frequency Per Million' people living in an area, and is abbreviated on the website as FPM."
So, Lashbrook showed up in United Kingdom, United States, New Zealand, Canada, Spain and France. I agree, Man's Lashbrooks started out in Devonshire England and came to the United States (via Canada for one year). Next I clicked on the United States and the site will tell you which states have the highest concentration of Lashbrooks living there. Again, I was pretty sure what states would pop up, from my research, and the site and I agreed. Interesting.
Above: Map of England showing the greatest concentrations of people with the surname Lashbrook, the darkest blue area is the Devonshire area, where Man' Lashbrook ancestors were from. Devonshire is still home to a number of Lashbrooks.
Back at the site, for some reason, I changed surnames and searched for Delawder. Well, now, this got interesting. Only two countries had that surname recorded, the United States and the United Kingdom. Click on the US, the top 5 regions (states) were West Virginia, Maryland, Virginia, Ohio, and Arizona. There is also a chart for the top 5 cities, they were: Ironton, Ohio; Broadway, Virginia; Mathias, West Virginia; Keyser, West Virginia and Basye, Virginia. The Virginia and West Virginia towns are very close to each other.
At this point, I clicked on Broadway, and Public Profiler/World Names gave me two charts, one with what they call "Top Forenames", or "given" names, and the second chart gives you "Top Surnames" in Broadway. I actually thought this was the one of the neatest parts of the site. Every surname they listed, I recognized from my research in the area.
Note: Delawder is only one spelling of this surname, of course. In the lines I am researching, it seems to change from DeLattre during the early 1800's.
I think you might find the site to be fun, give it a try.