Chapter 2: How Does a Search Engine Work?
In the previous chapter, we talked about the basics of SEO. Now, let’s look at what a search engine is, how it operates, and its role in SEO. By the end of this chapter, you will have a better understanding of Google’s ranking factors and algorithms. Read on to find out how to build a search engine-friendly website.
What is a Search Engine?
The search engine is an information retrieval tool on the Internet. It collects, processes, and analyzes information by utilizing computer programs and ultimately listing out the most relevant search results for users. The most popular search engine in the world is Google, with a market share of over 80%, followed by Bing, Yahoo, Baidu, and Yandex. Let’s take a look at how Google’s search engine operates.
The Operation of Search Engines
Search engines generally have three main functions: crawling, indexing, and ranking.
Crawling is the process of discovering new web pages and content. Each search engine has a unique web crawler (also known as “web spider”). Google’s web crawler is called Googlebot. Just like how real spiders crawl on spiderwebs, Googlebot visits different websites and crawls for new content, such as text, images, and videos. In the process of crawling, Googlebot will first visit several known web pages and obtain new URLs from reading the on-page content. By repeating these steps, Googlebot crawls through a large amount of information on the Internet. The Googlebot can also discover new URLs from other sources, including XML sitemaps.
Afterwards, Googlebot will store information it crawled in Google Caffeine, Google’s search index database for future use. This process is known as indexing.
When a user enters a query, Google retrieves relevant information from its search index. The search results will then be ranked and displayed according to factors such as the user’s location, language, device, web page content, and its relevance to the query. Google’s ever-changing algorithms heavily influence the ranking of results. It is hard to tell how much exactly each factor weighs in deciding the ranking. However, back in 2016, Google announced that content, backlinks, and RankBrain are the top three ranking factors. All three are associated with the algorithms below.
Keeping Up With Google’s Algorithms
Understanding Google’s algorithms are a must for anyone trying to improve their website ranking and gain a competitive edge in search results. Google algorithms are designed to provide users with the most relevant results and the best user experience through leveraging machine learning and big data analysis. Here are three major Google algorithm updates that changed SEO.
Content quality has always been a core focus for Google. Google Panda was released in 2011 to lower the ranking of low-quality and thin sites. It aims to provide users with the best-quality, most relevant and original search results. In other words, the followings are penalized:
- Thin Content: Web page that does not provide enough practical information
- Keyword Stuffing: Web page is excessively-packed with keywords in an attempt to increase its relevance to the user’s query and improve its position in the search results ranking
- Duplicate Content: Content lacks originality and are mostly copied from other websites
When people first noticed the connection between backlinks and webpage ranking, many tried to boost their search results ranking by establishing inorganic backlinks. Inorganic backlinks are unnatural, fake or tampered links that direct traffic to a webpage. In view of this, Google released Google Penguin, a site-wide algorithm update, in 2012 to monitor the quality of backlinks on websites. Google made it clear that any use of inorganic backlinks is considered as black hat SEO, which violates Google’s Webmaster Guidelines and may be penalized.
RankBrain is a machine-learning system launched by Google in 2015. It is regarded as a component of the Google Hummingbird algorithm update and is one of the most important ranking factors of Google search results. Hummingbird was initially launched in 2013 with the purpose to replace the previous keyword search technology with semantic search. To put it simply, Google’s search results are no longer based solely on the matching of on-page keywords with a user’s query terms, but instead, provide users with information that matches their search intent. RankBrain leverages artificial intelligence to more accurately grasp users’ search intent, analyze content quality, and optimize search results.
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