How Search Engines Work

Helping new employees learn SEO isn’t the easiest thing in the world. With so many ranking factors to consider, concepts to grasp, and processes to learn, the journey to SEO competence can be overwhelming.

Over the years, we’ve tried different approaches to help expedite the learning process for our new employees. What we found effective for many of our folks was giving them a solid foundation on how search engines work. We observed that once employees master the fundamental concepts, advancing their SEO knowledge becomes a simpler matter of adding to what they already know.

And while search engines have become increasingly sophisticated over the past three decades, the core of how they function has remained largely the same. Once an SEO trainee masters these mechanics, more advanced concepts in technical SEO, on-page SEO, link building, and other SEO facets start to make more sense.

So how exactly do search engines work? It’s a simple five-step process that’s the same whether you like using Google, Bing, or any other web portal. Here’s what we teach to our trainees:

1) Bot Release

If you ever wondered how search engines find and index websites, it’s all thanks to bots. Also known as spiders or crawlers, these tiny programs are released by search engines to websites. These bots read pages at the code level – meaning the HTML, JavaScript, CSS and other components – and make sense of them so search engines can figure out what queries they should appear for.

Search engines release bots arbitrarily to an initial “seed” group of websites and nobody knows which ones they are or how they’re chosen. Most experts in data retrieval and SEO do agree that search engines use large, popular websites like Wikipedia, The New York times, CNN, and other massive entities that have lots of external links as starting points in their crawl processes.

2) Bot Crawl

After being released to seed websites, bots will immediately start reading the designated webpages’ code. Bots will pay special attention to HTML code for hyperlinks that point to other webpages within and outside the website’s domain. This is important because links help bots traverse the Internet one webpage at a time. As soon as a bot finds all the hyperlinks in a page, it replicates itself according to the number of those links and sends its replicas to the links’ destination web addresses.

Once the replicas make it there, they repeat the code reading, link finding and bot replicating process. Bots do this again and again until they find a pretty large chunk of the Internet. It’s important to know that not all of the Web can be accessed by bots, though. Some pages are password-protected, some return server responses that prohibit bots from getting in, while others have special instructions in their webpages’ code instructing search engines to exclude specific webpages from their indices.

3) Caching

Contrary to popular belief, users don’t “search the web” when they enter a query on a search engine. If that were the case, it would take literal weeks for Google and other web portals to scan every webpage in existence and display their listings on your computer screen.

To make the delivery of search results almost instantaneous, search engines cache or store webpages in their databases. You see, when bots crawl the webpages they find, they don’t just look for hyperlinks., They also make copies of the webpages which are stored on search engine servers for analysis and quick retrieval whenever a relevant query is entered by a user.

So when Google and other search engines say you’re searching the web, it’s only half true. You’re actually searching the part of the web that they’ve crawled and stored in their data centers. This also explains why title tag, meta description and other on-page optimizations take a while to reflect on the live SERPs. Google needs to re-crawl your pages periodically to see and take note of the changes that have been made.

4) Algorithm Application

After storing webpages in its cache, Google applies its algorithms to better understand its context, authority, trustworthiness and ultimately, its relevance to they keywords that will represent it on the SERPs.

Google claims there are more than 200 ranking factors which it looks at to determine which webpages have the potential to meet a user’s query intent head on. Not all ranking signals are equal in weight, though. Backlinks and the breadth of a webpage’s content, for instance, hold a lot more sway on keyword rankings than things like site speed and header text.

5) Results Delivery

After the first four steps is the delivery of search results to our devices. In the early years of search engine history, the results were merely the usual 10 organic listings, but Google and other search engines have added feature after feature that made the SERPs a lot more nuanced in recent years. Things like instant answers, graphs, maps, rich snippets and other search features allow today’s users to spot the information they need more quickly and conveniently.


Search Research Subject Terms Vocabulary

Most modern search engines differ in their algorithms and the way they display results. For the most part, however, this classic five-step process has remained the same for almost 30 years. If you want to know more about how search engines work and how to optimize websites for greater visibility, watch the video embedded above and subscribe to our YouTube channel.