Set/update cookie on every page load

Question

I have a small snippet of code that does some work on a cookie on every page load.

(It's for affiliate tracking if you want to know why)

Where do I put this so it runs every every time a drupal page is loaded

Answer 1

This page should help:

http://www.nzwhost.com/article/displaying-drupal-mission-every-page

Answer 2

api.drupal.org/api/function/hook_boot