SERP stands for Search Engine Results Page. A SERP is a webpage loaded by a search engine in response to a search query made by an individual. Each SERP contains links that the search engine considers most likely to satisfy the intent of the searcher.
Search Engines work out which links to show by using spiders to index the web, and then algorithms to search that index and test the success of different results. Search Engines are constantly trying to serve up the best items they can, and so a low level of testing is constantly happening.
A SERP refers to an individual page from an individual search – eg page one on the search “dogs” that you specifically made, not all search results about dogs made by everyone. It is a useful way to talk about SEO, and page rankings for individual searches, as well as the technical make-up of search engines output.
SERPs used to include only organic search results, however, they now have many different types of results included on many different search engines. These include paid search results, as well as map results, video results, shopping results, news results, and more.