Google and other online services filter, or tailor their search results based on an algorithm. This relevance algorithm determines what results you get. A computer is picking results for based on what sites you view, what you click on, or other data that can be gathered from your browser. Think about it - how often do you see advertisements or recommendations based on where you shop, what you read, and what you watch online?
Can two people can search google using the same keywords and get different results? Listen to this fascinating TED talks to learn more about "filter bubbles" and how they may impact how you search for information online.