By default it is assumed that you only intend to use CodeIgniter to manage one application, which you will build in your application/ directory. It is possible, however

get_csrf_hash()

class CI_Encrypt encode($string[, $key = ''])

quotes_to_entities($str)

class CI_Loader library($library[, $params = NULL[, $object_name = NULL]])

If you find that no matter what you put in your URL only your default page is loading, it might be that your server does not support the REQUEST_URI variable needed to serve

remove_package_path([$path = ''])

vars($vars[, $val = ''])

set_error($msg)

or_like($field[, $match = ''[, $side = 'both'[, $escape = NULL]]])