This doesn't include the first few adverts that are paid for through Google Adwords and Bing Ads, a major source of income for these companies, but the unpaid adverts that immediately following them are ranks based on what is called domain authority which is based on links. You see, these search engines don’t look at every webpage to assess which one the best subject matter expert on keywords that user type in, but instead use algorithms to determine what other sites deem to be the authority on the matter. So for example, if you Google “Oregon Real Estate” you will not only get pages for the Oregon Real Estate Agency, but also Zillow and Realtor.com. This is because, not only are they related in keywords, but other webpages; brokerages, banks, and miscellaneous sites, link their pages to them. For example,midway through the first paragraph of this article, I have linked to the Oregon Real Estate Agency’s home page which tells search engines that this article; in some fashion, finds the OREA home page to be an authority.
Links are what make the world wide web, a web. There is no set layout in which every website occupies a space in relation to each other. All websites sit within various hosted or personally owned servers that our web browsers contact in order to pull the information. For example, this article and website is hosted by VistaPrint which either personally owns or rents servers that in turn maintain the data that makes up this specific article. Your computer requests the data associated with this specific URL, and the server sends the data back to be displayed by your browser.
Using real estate analogies, the web has no zoning for what content goes where. Data for web pages are simply stored on servers and have associated URLs that your computer requests. As a result, there is technically no order to the existence of the web, since it is merely numerous servers/computers pulling and sending data using a common language. Functionally, however, there is an order to it all, and that is thanks to links. Inbound and outbound links create a relationships between different web pages that, in turn, browsers use to rank which ones have greater authority over particular keywords.