How search engines work? Different types of search engine

Simply put, the very purpose of a search engine is to fetch any requested data from a huge database present online. The fun part being, a user doesn’t have to know where the information is stored. Google, Yahoo, Bing; have all gained widespread popularity and are commonly referred to around the household. But that’s not all. Besides such traditional search engines where people find information, there exist certain dedicated ones known as people search engines where you can dig up info about a long lost friend, a distant relative you haven’t heard from in eons. Or, more importantly, run a background check to verify information of an individual, like a neighbor, a potential employee you are looking to hire or a girl you have just met. No matter what kind of search engine it is, they all tend to work on a pre-set mechanism. In this post, we delve into knowing the different kinds of search engines that are out there, how it works, and the purpose it serves.

What makes search engines so important?

Search engines matter for one single reason; people looking for information for personal or professional needs.

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Google records more than a billion searches to gather relevant and useful info. It means a lot for businesses and other online content publishers to lure people to their website without having to pay anything. However, every search engine follows a set of guidelines and run their algorithm to help decide the ranking of websites in organic search results. For any site owner, it is necessary to optimize their sites for Google and other search engines to attract larger traffic. As such, the visitors can generate a good amount of revenue for any site owner, either through click-in advertisements or by purchasing a product or signing up for a service.

Knowing the different types of search engines

Search engines are mainly classified based on their working principle, namely:

  • Crawler based
  • Human-powered directories
  • Hybrid
  • Other types

Crawler based Search Engine
–As the name suggests, this type of search engine makes use of crawlers or bots for indexing any new content to the database in four steps, namely crawling, indexing, relevancy check, and fetching results. The frequency of crawling is directly dependent on the particular search engine and might take some time between the crawls. This is precisely the reason why one can sometimes see old or deleted content getting pulled up in the search results.

Right after crawling, the next step is indexing, which is nothing but a process through which words, as well as expressions, are identified that describes a webpage best. Such terms are referred to as keywords, and a particular page is assigned to a set of identified keywords. At times, when a crawler fails to understand the very meaning of a page, a site may rank low among search results. Herein, lay the essence of optimizing the pages for crawlers to gain an easy understanding of the content. When the crawlers pick up the correct set of keywords, the webpage can be assigned to a particular set of keywords to rank high.

It’s typical for search engines to compare search strings by the indexed pages. Further, it is most likely that one or multiple pages might contain search strings, responsible for relevancy check. Now, there are several algorithms to check relevancy, and each algorithm carries a relative weight for commonly dealt factors like meta tags, links, or keyword density. That is why different search engines pull up different search results for a similar search string. By now, it is mostly known to an educated net user, that search engines change their algorithm periodically. For any site owner to rank at the top, he will need to adapt the webpages to all such latest changes, which calls for permanent devotion towards SEO, to be at the top of the game.

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Retrieving results is the last step for a search process to be completed, and displaying them in order. Google, Bing, Yahoo, Baidu, DuckDuckGo, AOL are all examples of crawler-based search engines.

Human Powered Directories–Also known as Open Directory System, Human Powered Directories depend primarily on human activities for the listings. It generally begins with a site owner submitting a short description of his site to the directory along with the relevant category. The submitted site then goes through manual reviewing before it gets added to the appropriate category or gets rejected. As such, one needs to enter keywords in a search box matching the description of the site. In other words, any modification of content doesn’t influence the search results. Yahoo Directory, DMOZ are perfect instances of directories that are human-powered.

Hybrid Search Engines–Hybrid Search Engines make use of both crawler-based as well as manual indexing for the listing of sites. A majority of search engines like Google make use of a crawler-based mechanism as the primary one and further supported by human-powered directories as a secondary method. The search engine may accept the description for a particular webpage derived from human-powered directories and display the same in the final search results. Over time, human-powered directories are turning obsolete as the crawler mechanism gains dominance. Having said that, there still exists manual filtering for search results for sites that are copied or spammy. Such website owners require that they take corrective action to re-submit the same for search engines. The web experts are responsible for manual reviewing of the site before it can be included in the search results. So, the crawlers control the whole process, which runs by manual monitoring and displays search results naturally.

Other Search Engines

Besides the three major types of search engines, other kinds make use of use bots, which are exclusively used for displaying videos, images, news, and local listings. For instance, Google News which can be specifically used to search for news from several different sources. Metasearch engines like Dogpile function to collect meta-information from pages of other search engines as well as directories to display the same in search results. Also, Semantic search engines like Swoogle that cater to offer search results that are accurate and true to a particular location, where the contextual meaning of queries is taken into consideration.


Wrap Up 

The halcyon days of the Internet saw human-powered search engines gaining popularity as a significant source of information. Fast forward to 2019, where automation and artificial intelligence rules the roost, tech giants like Google are driving changes to garner maximum benefit. As such, it is seemingly impossible for human-powered search engines to thrive in the hands of crawler-based ones controlling a sea of information without any manual interference. 

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