the role of default controller in your codeigniter
the question arises what part played by default controller in codeigniter
it is the root of every thing in other words
you must see its logic otherwise your programming with codeigniter will be null and void .
it is the root and important part of codeigniter
in other words, codeigniter will not work without it. so have clear concept of this thing .
it is found in your application/routes.php file
for more you have to go click here