getting httpcontext in solution controllers

Hi, beginner here slowly getting to know sitecore better and better.

 

I add support in a sitecore solution for a query parameter that can result in some things being displayed differently in the view.

So ive been told that it would probably be a good idea to construct a cookie that could do this, and that it would not be a good idea to simply take the query string into the relevant controller method.

 

So what I want to ask is: Is there someway that i can get the query string in a relevant controller method/action, using httpcontext/cookie?