One of the big trends of recent years is personalization of search.
Google especially has been working intensively on this.
What you see in a search result may be different than someone else doing the same search from right next door.
There has been a lot of talk about that meaning “the end of search as we know it.”
That kind of thing comes up all the time, every time Google makes an important change, but it is always greatly exaggerated.
A new interview with a Google staff member makes this very clear in regards to personalization:

In fact only small changes are made to a results page based on personalization.”

There is also new information in this interview about exactly what Google does and doesn’t do, and also making a clear distinction between personalization and what Google calls “context.”
How Google Does Personalization
Read it!