How do search engines make money?

Search engines have two types of search results: 

1. Organic results from the search index. You can’t pay to be here.
2. Paid results from advertisers. You can pay to be here.

Each time someone clicks a paid search result, the advertiser pays the search engine. This is known as pay-per-click (PPC) advertising, and it’s why market share matters. More users mean more ad clicks and more revenue.