If you want to know that, Read
The Ultimate Guide to the Google Search Parameters and Advanced Google Search. The google search query structure is broken down into chunks and has detailed information about their purpose. You will get to know what the parameters in your search queries are.
The following are some of the decodings of Google's search query syntax.
Basic Search URL:
https://www.google.com/search?
hl=en
&q=test
&btnG=Google+Search
Advanced Search URI
https://www.google.com/search?
as_q=test (query string)
&hl=en (language)
&num=10 (number of results [10,20,30,50,100])
&btnG=Google+Search
&as_epq= (complete phrase)
&as_oq= (at least one)
&as_eq= (excluding)
&lr= (language results. [lang_countrycode])
&as_ft=i (filetype include or exclude. [i,e])
&as_filetype= (filetype extension)
&as_qdr=all (date [all,M3,m6,y])
&as_nlo= (number range, low)
&as_nhi= (number range, high)
&as_occt=any (terms occur [any,title,body,url,links])
&as_dt=i (restrict by domain [i,e])
&as_sitesearch= (restrict by [site])
&as_rights= (usage rights [cc_publicdomain,cc_attribute,cc_sharealike,cc_noncommercial,cc_nonderived]
&safe=images (safesearch [safe=on,images=off])
&as_rq= (similar pages)
&as_lq= (pages that link)
&gl=us (2-digit country code in lowercase)
&btnI=I%27m+Feeling+Lucky