mod_rewrite what is it and what does it affect?

I was told by someone reviewing my issue with my website that the problem is with the lack of setting mod_rewrite. What is the affect of mod_rewrite on CI3 on an apache  web server?

proof that an old dog can learn new tricks

It allows you to redirect an url to a file without having the filename in the url. With CodeIgniter you need mod_rewrite to remove index.php from the url. The rules in .htacess will tell Apache to redirect the queries to index.php, which is the front controller. Read this page: https://codeigniter.com/userguide3/gener...x-php-file

So you can have something like

Code:

http://localhost/blog/whatever

...instead of

Code:

http://localhost/index.php/blog/whatever