Is ISBN needed for a self published e Book

I am working on creating an e-book. All the content and pics etc. are my personal work.

Should I apply for an ISBN number? Does it benefit me in anyway?

Based on some Googling it is issued by NCL National Central Library in Taiwan and it does not seem to be a statutory requirement in Taiwan, nor is it related to or associated with copyright ownership. If anyone has idea or experience with this please share your inputs. Thanks!