Php Experts,

I am a complete beginner in Php. Trying to learn Php 7 as much as I can. I need your help to point me to the right direction.
What kind of method in Php 7 is used to track URLs belonging to a foreign domain ?

I mean, you all know that searchengines track clicks to links presented by their SERPs. So, if gidforum.com is listed under the keywords "PHP forum" on Google SERP then when you click gidforum.com on the Google SERP then that link is bound to have Google's tracking link. In short, you'll click the Google tracking link and then get redirected to gidforum.com. But once you enter gidforum.com then the links you find on the site would not have Google's tracking links as Google has no control over the linking method inside gidforum.com.

However, with anonymous web proxies, the story is different. Let me show you how.
First go to:
http://anonymouse.org

and type 'loudgobs.com/blog' to anonymously browse the blog.
Once the web proxy loads the blog, hover your mouse over the blog's links and you'll see all the links contain the web proxy's tracking links even though the blog itself does not house the web proxy's tracking links.
Go to the blog direct and see for yourself and check it out:

http://www.loudgobs.com/blog/

Now, view the blog via the web proxy:

http://anonymouse.org/cgi-bin/anon-www.cgi/http://www.loudgobs.com/blog/

and hover your mouse over the blog links and see whether the web proxy's tracking links exist or not. I know the proxy is somehow tracking via the frame or iframe or cloaking technique but ....

Q1. What php 7 technique is it using to create these tracking links so it looks as if the tracking links are hosted by the blog ? 
I need to learn how to create these tracking links. 

Q2. Which part of Php 7 do I need to learn and can you recommend some tutorial links? 

Q3. Are you aware of any video tutorials on youtube? What keywords should I search for?

affiliate linking with php 7 ?
referral linking with php 7 ?
self replicating linking with php 7 ?
tracking links with php 7 ?
tracking via GET method ?
tracking via POST method ?
Anything else ?

Thank you for your help. Your answers should be helpful to all newbies who read your reply!