SERP stands for “search engine results page.” This is the page that shows up when a search engine returns results in response to a keyword query. The SERP is a collection of organic (or unpaid) search results and paid search results.
As search engines have advanced, the search results page has become much more comprehensive. Besides displaying organic search results, SERPs have also started to include advertisements and sponsored content. Typically, search engines are programmed to group different types of results together on one SERP.
The search engines that search engines use, such as Bing, Yahoo, and Google, have slightly different algorithms that determine their rankings. However, the SERPs generally consists of 10-20 links. The links that Google contains may change over time, but in general, the top links pertain to content which Google deems to be most relevant to user’s search terms.