The full form of SERP is Search Engine Result Page nothing but a page on the search engine like Google or Bing that returns a list of webpages, usually 10 per page, in response to the search query you entered. Even if you didn’t knew what it meant, you now know that you have been using it for a long time.
Each listing on the SERP page contains the title of the webpage in question, a brief description of the webpage which is usually around 170 characters, and a link to the webpage. When you click on this link, you are taken to the webpage directly.
There are three different types of SERPs that you will find when searching for something on your favorite search engine. The first is the one that was found by the crawlers or spiders of the search engines which was later indexed by the search engine so the results could be displayed later when someone searches for something that matches the description and keyword.
The second one is ads or sponsored listings that appear on the top of any search listing. This means that the owner of the website has paid dollars to the search engine to display its links every time someone searches for the specified keywords. They always appear on the top with a yellow background to distinguish them from normal listings. You will find a disclaimer below them.
The third kind is the one that was added to the search engines manually by the web designer or the owner of the website to be indexed in the search engine directory. These are usually the people who are actively promoting their websites using SEO tactics and actively undertaking Internet Marketing.
Every time you perform a search, you will notice that there are thousands if not millions and billions of listings for the search term. But the search engine only shows what it deems to be the most relevant listing.