Most search on the web is keyword based: you type keywords relevant to your query into a search box, and the results of the search should list content that matches your keywords. Whether you are using a search box on a website, on YouTube, or Google, this outlines the very basic way we expect search to work. The search engine which is returning results is trying to match your keywords to the content it has indexed, and is also trying to determine how to rank the results so that you get the most relevant content at the top of your search results page.