"Pwy dych chi?"
Translation:Who are you?
'Pwy dych chi' ('dach chi' in NW) is the formal or plural form of 'Who are you?"
'Pwy wyt ti' is the informal singular form.
Would you use the informal when talking to children? I can't imagine any other scenario one would be comfortable enough to speak informally to another who they don't yet know.
Is there a cultural thing? When would I use each?
This is explained in the course notes. In short:
- ti is only used with an individual with whom you are on familiar terms. It would also be used with a child.
- chi is used with any two or more people, and with an individual with whom you are not on familiar terms.
Or just about every language I can think of. One of the glaring deficiencies of English - my mother tongue - to my mind is the lack of informal & formal versions of 'you'. Forget 'thou' & 'thee'; leave these forms to the Bible & Shakespeare. Forget "y'all", which, even if acceptable, is only a plural form. English is now stuck with this lack as it is far too widespread to introduce an extra pronoun and, anyway, there is no language academy to do so (for which last, 'Vive la liberté!).