When an user "googles" somethings, there are multiple parameters being passed on to the google search service.
Since the example you put in the description is the most basic one, the url looks small.
Your query utlizies the following three parameters:
q: the query string google is passing on to the search service.
oq: the query string you typed on google.
aqs: stands for assisted querry stats and is found when searching Google through Chrome omnibox. Mainly used for logging purposes the parameter contains impressions of all auto complete matches shown at the query submission time.
sourceId: Type of the source
ie: type of encoding, UTF-8 is mostly used.
If you search for images, maps, videos etc, the parameter list would be much bigger.