CodeIgniter is an application development framework, which can be used to develop websites using PHP.
CodeIgniter comes with the outstanding capabilities that enable it to provide an exceptional performance in a very short period of time.
MVC framework is very common for developing custom solutions with PHP. There are many PHP MVC frameworks available on the web. CodeIgniter and Laravel seem to be the most popular among all of them. But the choice of web framework differs from one developer to another.