Of course you can work with cookies inside your Rails application. This is, again very similar to working with parameters or sessions. Consider the following example:
#here we want to store the user name, if the user checked the "Remember me" checkbox with HTML attribute name="remember_me"
#we have already looked up the user and stored its object inside the object-variable "@user"
cookies[:commenter_name] = @user.name
else # Delete cookie for the commenter's name cookie, if any