SERP, or Search Engine Results Page, is the page displayed by search engines in response to a user's search query. It includes a list of results that are most relevant to the search term, which can be websites, images, videos, news articles, and sometimes direct answers or featured snippets. SERPs also include paid advertisements relevant to the search terms. The layout and features of a SERP can vary based on the search engine and the specific query, with factors like SEO, content relevance, and site authority affecting the ranking of results.