Search engines are an essential part of the internet, allowing users to quickly and easily find the information they need. There are four main types of search engines: crawler-based search engines, hybrid search engines, special-purpose search engines, and metasearch engines. Crawler-based search engines use a crawler, bot, or spider to crawl and index new content in the search database. Popular crawler-based search engines include Google, Bing, and Yahoo.
These search engines follow four basic steps before displaying any site in search results: crawling, indexing, processing, and calculating relevance. During the early days of the Internet, human-powered search engines were a popular and important source of information. However, as technology advances and automation becomes more prevalent, these types of search engines have become obsolete. Hybrid search engines use both manual and crawler-based indexing to include sites in search results.
For example, Google can take the description of a web page from human-created directories and display it in search results. As human-powered directories disappear, hybrid types are increasingly becoming crawler-based search engines. Special-purpose search engines are used on a very small scale for specific tasks. These types of search engines are powered by artificial intelligence or tracking technology with minimal human intervention.
Examples of special-purpose search engines include Shopping, Local Search, Domain Name Search, Freeware & Shareware Software Search, and List searches. Metasearch engines are services that will make your search go through several more popular search engines. By “digging deeper” into categories and subcategories, you will eventually land on specific pages that should be relevant to your query. Optimizing websites for search engines is an essential part of any website owner to reach a large audience.
To improve your website's ranking in search engines, it's important to understand the basic criteria with which search engines index and retrieve documents.