Online search engines are tools that help users find information on the internet. They work by indexing web pages and using algorithms to rank them based on relevance to a user's query. Popular search engines include Google, Bing, and Yahoo, which allow users to enter keywords or phrases to retrieve a list of related websites. When a user types a query, the search engine quickly scans its database and presents results in a matter of seconds. These results often include links to articles, images, videos, and other content, making it easier for users to access the information they need.