What Is a Search Engine? Definition Plus 10 Examples
You may use a search engine every day—but do you really understand what it is? Here's a rundown of the basics.
What Is a Search Engine?
Also known as a web or internet search engine, a search engine is a (usually web-based) computer program that collects and organizes content from all over the internet. The user enters a query composed of keywords or phrases, and the search engine responds by providing a list of results that best match the user's query. The results can take the form of links to websites, images, videos, or other online data.
How Do Search Engines Work?
The work of a search engine can be broken down into three stages. Firstly, there is the process of discovering the information. Secondly, there is the organization of the information so that it can be effectively accessed and presented when users search for something. Thirdly, the information must be assessed to present search engine users with relevant answers to their queries.
These three stages are usually called crawling, indexing, and ranking.
Crawling
Search engines use pieces of software called web crawlers to locate publicly available information from the internet, which is where this process gets its name. Web crawlers can also sometimes be referred to as search engine spiders. The process is complicated, but essentially, the crawlers/spiders find the webservers (also known as servers for short) which host the websites and then proceed to investigate them.
A list of all the servers is created, and it is established how many websites are hosted on each server. The number of pages each website has, as well as the nature of the content, for example, text, images, audio, video, is also ascertained. The crawlers also follow any links that the website has, whether internal ones that point to pages within the site or external ones that point to other websites and use them to discover more pages.
Indexing
Information found by the crawlers is organized, sorted, and stored so that it can later be processed by the algorithms for presentation to the search engine user. This is known as indexing. Not all the page information is stored by the search engine, instead, it's just the essential information needed by the algorithms to assess the relevance of the page for ranking purposes.
Ranking
When a query is entered into a search engine, the index is scoured for relevant information and then sorted into a hierarchical order by an algorithm. This ordering of the search engine results pages (SERPs) is known as ranking.
Different search engines use different algorithms and so give different results. Over the years, algorithms have become more and more complex as they attempt to present more relevant and accurate answers in response to the queries of search engine users.
10 Examples of Search Engines
To better understand the mechanics and practical use of search engines, let's take a look at some of the most commonly-used ones.
1. Google
Google is the biggest search engine in the world by far. It handles over 5 billion searches each day and has a market share of over 90% at the time of writing (August 2019). Developed originally by Larry Page and Sergey Brin in 1997, Google has become so successful that it has become synonymous with search engine services, even entering the dictionary as a verb, with people using expressions such as: "I googled it" when they've searched for something online.
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2. Bing
The origins of Microsoft's Bing can be found in the technology company's earlier search engines, MSN Search, Windows Live Search, and Live Search. Bing was launched in 2009 with high hopes that it could usurp its rival Google, but despite attracting many fans, things haven't quite worked out that way. Even so, Bing is the third largest search engine worldwide after Google and Baidu. It is available in 40 different languages.
3. Yahoo!
Yahoo! Search is another big player in the search engine world. However, for much of its history it has supplied the user interface but relied on others to power the searchable index and web crawling. From 2001 to 2004, it was powered by Inktomi and then Google. From 2004, Yahoo! Search was independent until a deal was struck with Microsoft in 2009 whereby Bing would power the index and crawling.
4. Ask.com
Originally known as Ask Jeeves, Ask.com is a little different from Google and Bing as it uses a question and answer format. For a number of years, Ask.com was focused on becoming a direct rival to the big search engines, but nowadays, answers are supplied from its vast archive and users contributions, along with the help of an unnamed and outsourced third-party search provider.
5. Baidu
Founded in the year 2000 by Robin Li and Eric Xu, Baidu is the most popular search engine in China and the fourth most visited website in the world, according to Alexa rankings. Baidu has its origins in RankDex, a search engine previously developed by Robin Li in 1996. As well as its Chinese search engine, Baidu also offers a mapping service called Baidu Maps and more than 55 other internet-related services.
6. AOL.com
AOL, now styled as Aol. and originally known as America Online, was a big player in the early days of the internet revolution, providing a dial-up service for millions of Americans in the late 1990's. Despite AOL's decline as broadband gradually replaced dial-up, the AOL search engine is still used by a significant minority of searchers. On June 23, 2015, AOL was acquired by Verizon Communications.
7. DuckDuckGo
DuckDuckGo (DDG) has a number of features that distinguish it from its main competitors. It has a strong focus on protecting searchers' privacy, so rather than profiling users and presenting them with personalized results, it provides the same search results for any given search term. There's also an emphasis on providing quality rather than quantity when it comes to search results. DDG's interface is very clean and not overladen with adverts.