Exact location of CI files

What I do, which is by no means the only way to handle this...

/htdocs/xxx is my project root, a.k.a my repository
/htdocs/xxx/application is my code
/htdocs/xxx/public is my documenet root, containing index.php, .htaccess & any images, CSS, etc
/htdocs/xxx/system is the framework

I map a subdomain virtual host entry to the public folder inside my project.

See https://github.com/jedi-academy/CodeIgniter3.1-starter1

ps - The above *is* the structure/strategy we are using for CodeIgniter4