Is a language subdomain required instead of subdirectory for multilingual SEO? [duplicate]

Question

In my site, the multilingual path is look like:

e.g. www.example.com/en/index.html

I want to ask is it necessary to use sub domain for SEO best practice?

e.g. www.en.example.com/index.html

Answer 1

Google say you can use either: https://developers.google.com/search/blog/2010/03/working-with-multilingual-websites