A Web search engine is a program that is designated to search for information on the Internet. The results that are obtained are categorized in a variety of formats such as web pages, images and videos and are collectively called “hits”. When the results are displayed the search engine highlights the index of keywords in the search listings and shows the user where those keywords were found.
Search engines typically send out search engine bots or spiders to a website to read the content that is displayed on it. When the content is effectively scanned by the bots, another program known as an indexer is sent to the website. This program typically saves all the content on the website and catalogues it according to the keywords contained in it. In order to weed out websites with irrelevant content, every search engine uses its own unique algorithm. These algorithms are often altered and updated periodically by the search engines.
How do all web search engine work?
With over 200 million websites in existence it would be impossible for anyone to locate information and data without the help of search engines. When a search query is requested by a user, the search engine immediately responds to the keywords by displaying the previously indexed pages that contain the same relevant keywords.
There are 3 different types of search engines:
• Search engines powered by humans
• Search engines powered by bots( crawlers and spiders)
• A hybrid of both varieties
Search engines (Google, Yahoo, Bing, ect.) that are powered by bots leverage the use of crawlers or automated software to generate results. These bots read everything from the content displayed on the website to its Meta tags as well as the inbound links that the site is connected to. The crawler simultaneously indexes all the content contained in the website and relays it back to its database, where the data is catalogued according to the keywords and phrases. Depending on the relevance and quality of the website, the crawler will periodically return to see if there are any changes made so that it could update these changes in its vast database of information.
Search engines powered by humans depend entirely on the information that is indexed and catalogued by humans. One of the major drawbacks of human powered search engines is that the data indexed is very limited compared to search engine bots.
When a user makes a search engine request, it is the crawler that actually does the searching and not the user himself. This is one of the reasons why sometimes search engines generate dead or invalid links. This is due to the fact that all search engines are based on the indexed information previously stored by the bots. If these indexes have not been updated when a particular website shuts down, the results would display the dead link.
You might wonder why some search engines produce different results? This is due to the fact that every search engine has its own unique algorithm to rank web pages. In other words the search results would rank websites according to what the algorithm considers relevant to the corresponding search query.
The algorithms are also used to understand how certain websites are linked to one another. This helps the search engine to determine the content of a particular page and its relevance to specific keywords. Using this information a search engine is able to weed out irrelevant sites that engage in spamdexing and keyword stuffing from its listings.