Search engines work by crawling the Internet using bots called crawlers or spiders. They follow links from page to page looking for new content to add to the search index. When you use a search engine, relevant results are pulled from the index and ranked according to an algorithm.
If this sounds complicated, it’s because it is. But if you want to rank higher in search engines in order to drive more traffic to your website, you need a basic understanding of how search engines work, index, and rank content. In that case, it will be easier to make digital marketing with SEO service for your business.
What are search engines?
Search engines are tools that find and rank web content that matches a user’s search query.
Each search engine consists of two main parts.
- Search index. Digital library of information about web pages.
- Search algorithms. Computer programs that rank matched results from a search index.
Examples of popular search engines include Google, Bing, and DuckDuckGo.
What is the purpose of search engines?
Every search engine strives to provide users with the best and most relevant results. That’s how they get or keep market share – at least in theory.
How do search engines make money?
Search engines provide two types of search results.
- Organic results from the search index. You can’t pay to get in here.
- Paid advertising from advertisers. You can pay to get here.
Every time someone clicks on an ad in search, the advertiser pays the search engine. This is called pay-per-click (PPC) advertising.
That’s why market share matters. More users mean more ad clicks and more revenue.
Why should you care how search engines work?
By understanding how search engines find, index, and rank content, you can rank your site in organic search results for relevant and popular keywords.
If you can rank high for these terms, you will get more clicks and organic traffic to your content.
What is the most popular search engine?
Google is the search engine that most SEOs and website owners are interested in because it is able to send more traffic than any other.
Most well-known search engines such as Google and Bing have trillions of pages in their search indexes. Before talking about ranking algorithms, let’s take a closer look at the mechanisms used to create and maintain a web index.
How search engines build their index
Let’s walk through the process, step by step:
- URLs
- Scanning
- Processing and rendering
- Indexing
URLs
It all starts with a list of known URLs. Google discovers URLs through a variety of processes, but the most common ones are the ones below.
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From backlinks
Google already has an index containing trillions of web pages. If someone adds a link to one of your pages leading from one of them, Google will be able to find it in that index.
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From sitemaps
Sitemaps list all the important pages on your site. If you submit your sitemap to Google, it can help them discover your site faster.
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From add URLs
Google also allows you to add individual URLs through the Google Search Console.
Scanning
In this step, a computer bot (crawler), such as Googlebot, visits and downloads the discovered pages.
It’s important to note that Google doesn’t always crawl pages in the order they find them.
Google queues URLs for crawling based on several factors, including:
- PageRank URLs;
- how often the URL changes;
- is it new or not.
This is important because it means search engines may crawl and index some of your pages before others. If you have a large website, it may take time for search engines to fully crawl it.
Treatment
Processing is the stage in which Google recognizes and extracts key information from crawled pages. No one but Google knows all the details of this process, but the important parts for us to understand are extracting links and saving content for indexing.
Google needs to get page renders in order to fully process them, and this is where Google executes the page’s code to understand how it looks to users.
With this, part of the processing happens both before and after rendering, as you can see in the diagram.
Indexing
In this step, the processed information from the crawled pages is added to a large database called a search index. It is essentially a digital library of trillions of web pages from which Google search results come.
This is an important point. When you enter a query into a search engine, you are not looking for relevant results directly on the web. You are performing a search in a search engine’s index of web pages. If a web page is not in the search index, search engine users will not find it. That’s why it’s so important to get your site indexed on major search engines like Google and Bing.
How search engines rank pages
Discovering, crawling, and indexing content is just the first piece of the puzzle. Search engines also need a way to rank relevant results when a user searches. This is a job for search engine algorithms.
Each search engine uses unique algorithms to rank web pages. But since Google is the most widely used search engine (at least in the Western world), that’s what we’re going to focus on in the rest of this guide.
Google has over 200 ranking factors.
No one knows all of these ranking factors, but we do know about the key ones.
Let’s briefly discuss them.
- Backlinks
- Relevance
- Novelty
- Thematic Authority
- Page load speed
- Mobile optimization
How search engines personalize search results.
Search engines understand that different people like different results. Therefore, they tailor their results for each user.
If you’ve ever searched for the same thing across multiple devices or browsers, you’ve probably seen the effect of this personalization. The results are often displayed in different positions depending on various factors.
It is because of this personalization that if you are doing SEO, you are better off using a dedicated tool like Ahrefs Rank Tracker to track your rankings. The positions claimed in these tools are likely to be closer to the truth because they surf the web in such a way that search engines get the least amount of information for personalization.
How do search engines personalize results?
Google states: “In order to provide users with the most relevant and relevant information, we take into account information about their location, previous requests, Google Search settings, etc.”.
- Location. If you enter something like “Italian restaurant”, all results on the maps will be local restaurants.
- Language. Google knows it doesn’t make sense to show results in English to users in Spain.
- Search log. Perhaps the most obvious example of Google using search history to personalize results is when it “ranks” a result you previously clicked higher the next time you perform the same search.
Let’s summarize.
Understanding how search engines work is the first step to ranking higher on Google and getting more traffic. If search engines can’t find, crawl, and index your pages, they’ll be uncompetitive before you even start optimizing them.
If you want to know how to do this and how to get started optimizing your site for SEO, read our SEO Basics guide.
