A search engine helps you overcome these problems and navigate through the Internet and get the information that you require quickly and accurately. The two basic approaches to searching the Web are search engines and subject directories. They are not the same. The difference is how listings are compiled. Search engines crawl the web and compile a database of websites.
Some search engines maintain an associated directory from where it throws up results for searches.
Being included in a search engine's directory is usually a combination of luck and quality. Reviewers often keep an eye on sites that would be of interest to their users and add those sites to their directory. The sites listed in a directory are classified depending on the subject of their content. You submit a short description to the directory for your entire site, or the editors write one for sites they review. If you are focused about what information you want on the web, a directory search will be the right choice for you.