A search engine is a "tool that searches the web".
A search engine is a software program that searches a database of web pages and provides a list of results that are relevant to the user's search query. The user enters a query into the search engine, and the engine uses complex algorithms to search through billions of web pages to find the most relevant results.
Search engines are designed to make it easier for users to find information on the web. They can search for all types of content, including web pages, images, videos, news articles, and more. Popular search engines include Google, Bing, Yahoo!, and DuckDuckGo.
It's important to note that search engines do not actually search the entire web. Instead, they search their own database of web pages that have been crawled and indexed by their algorithms. This means that it's possible for some web pages to be excluded from search results if they have not been indexed by the search engine.