browse-url-of-file is an interactive autoloaded compiled Lisp function in `browse-url.el'.

(browse-url-of-file &optional FILE)

Ask a WWW browser to display FILE.
Display the current buffer's file if FILE is nil or if called
interactively. Turn the filename into a URL with function
`browse-url-file-url'. Pass the URL to a browser using the
`browse-url' function then run `browse-url-of-file-hook'.