Every answer narrows down the number of the persons. "Man or woman", for example, halfs the available search space. The subject being "French" makes it 100 times smaller (ignore all non-French entries in its database), etc.

Plus, depending of how the coded it, it can learn new people too (it asks you if it can't guess after enough tries). Most people (and it's used by 100s of thousands) ask for the same persons more or less (current stars, politicians, famous authors and painters, musicians, religious figures, comic heroes etc).

And what people consider "obscure" is not always really obscure either. E.g some might think that, say, Captain Beefheart is obscure. And compared to Justin Bieber he is. But he too is known by hundrends of thousands, so, he's not really difficult to find and store in a database of musicians.

I've had it stumble several times with more obscure people (e.g out of mainstream musicians), and in the end it gave up and asked me their names.

(Btw, the website also has a mobile app available, at least for iOS).