What is Google doing when I click a search result?

Question

Say I go to google.com and search for "Klaus Harmony". The first result is a Wikipedia page. If I open the network tab and click "preserve log", so that the requests won't be cleared upon navigation, I see 2 things:

A POST request, with the status (ping)

A GET request which carries the HTTP Referrer of "http://google.com"

My questions are:

1. What are they trying to accomplish here, especially with that strange first request?
2. How are they changing the HTTP Referrer?

Answer 1

1. I'd say its to check if the site still works or should you see see the last crawled version of the page if the ping fails, another thing might be for google analytics purposes

2. if you search at google.com, google.com is your referrer, there is no need to change anything. You can modify it to omit the ?Q=== part by proper meta, you can read here: http://wiki.whatwg.org/wiki/Meta_referrer