Where does the default mb_internal_encoding() value come from?

Question

If I were to write a new php file, and include echo "current mb_internal_encoding: ".mb_internal_encoding() , where would the output value come from? How is it "decided" / how is it governed?

Background: I wrote a web app where I thought I had done everything to set the whole site to utf-8 and found that I still needed to set this value manually...

Answer 1

It depends on the setting of mbstring.internal_encoding in php.ini.