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How Do Search Engines Work?

Search engines are searchable databases made up of two main parts: search indexes and search algorithms. Their overall goal is to provide users with the most relevant results based on the search they are making.


Search engines have two types of search results – organic and paid. Organic results come from the search index and paid results are paid to be there by advertisers. Paid results operate under a pay-per-click system where the advertiser pays the search engine every time someone clicks on their website.


What Search Engines Look For

Search engines play a key role in helping us find information on the internet. To keep search results as relevant as possible, search engines operate by performing three essential tasks. This includes:

  • Crawling
  • Indexing
  • Ranking

These tasks involve exploring web pages, understanding their content, and presenting relevant information to users based on their search queries.

Google continuously seeks out new and updated web pages to add to its list of known pages, a process known as “URL discovery.” This can happen through direct visits, following links from known pages, or by submitting a list of pages for Google to crawl.


Google uses a program called “Googlebot” to crawl billions of web pages Here it fetches pages and determines which sites to crawl, how often, and how many pages to fetch from each site. Crawling is based on an algorithmic process and is regulated to avoid overloading sites.

Crawling URLs is a task performed by computer programs known as “crawlers” or “spiders.” These crawlers visit web pages to extract HTML content and identify links. HTML is the language used to mark up web page content and enables crawlers to differentiate between text and hyperlinks.

When examining HTML code, crawlers identify elements like paragraph tags for text and anchor elements for links. By parsing HTML, crawlers extract links from web pages and schedule them for further crawling. This effectively creates a loop of feedback for discovery. This process allows search engines to find and index web pages, making internal and external links essential for efficient crawling and exploration of the internet.

How Does Google Determine Crawling?

Google has what is referred to as the “crawl budget.” These are the resources issued by Google for crawling a website.

This is influenced by two primary factors:

  • Server Speed

This determines how much Google can crawl without negatively impacting user experience.

  • Website Importance

Websites with high relevance and frequent content updates are crawled more often.

For instance, major news sites receive frequent crawls due to their dynamic content, whereas smaller businesses with fewer links may have a lower crawl budget.

Google conducts two types of crawling during indexing:

  • Discovery

This is where Google finds new web pages to add to the index.

  • Refresh

This is where Google identifies changes in existing indexed pages.


After crawling, Google indexes pages. As search engines crawl the web, they use microdata called “Schema” to collect web page content to build an index – much like the index found in a textbook. This index allows for quick searching and retrieval of information. This index includes the discovered URLs and key signals such as:

  • Keywords on the page
  • Type of content
  • How recently updated is the page is
  • Previous engagement of the page

Google indexes processes and analyzes features such as textual content, tags, attributes, and other elements like images and videos. Google also determines canonical pages and collects signals about their content, which may be stored in the Google index.

Search engines parse HTML documents to extract links and text content, which they use to generate an inverted index associating words with web page URLs. This indexed data, along with metadata collected about each page, determines which URLs appear in search results.


Crawling and indexing of web pages occur automatically and continuously, with the index being updated in real-time. However, delivering search results is driven by user queries, and search engines use ranking algorithms to determine the most relevant results. These algorithms consider factors such as the presence of search query words on web pages, their combinations, appearance in titles and URLs, and more.

Why Does Ranking Matter?

There are many different types of search engines – Bing, Yahoo, Google, etc. However, Google more than 90% of those web searches are made on Google. The ranking determines where your web page shows up when someone conducts a search. The higher the ranking, the closer to the top the page will appear, increasing the amount of traffic your page will receive.

Why Might a Website Have a Low Ranking?

If your website is not appearing in search results, it may be because Google is penalizing your site. There are several different reasons this could be happening:

  • Difficulties with crawlers

If your website is too young, crawlers may not have had the chance to analyze the page yet. Additionally, your website can be penalized if your website navigation is too difficult for effective crawling.

  • Lack of external links

You may be penalized for not having any outgoing links to other websites.

  • Crawler Directives

Your website may be blocking search engines if it contains“crawler directives” – a basic code that instructs search engines how to crawl certain pages.

  • Spam Penalties

Google also penalizes websites for it identifies as spam to get better SEO. This may include link spam, keyword stuffing, cloaking, and more.

Submitting a Website

For website owners aiming to attract organic traffic, submitting their websites to search engines can expedite their online visibility. While search engines typically automatically index websites, manual submission can accelerate the process and ensure timely inclusion in search results.

Submitting a website involves providing an “XML sitemap.” This acts as a roadmap for search engine crawlers to efficiently index website content. Most content management systems generate sitemap files automatically, simplifying the submission process.

Google requires website integration and verification through Google Search Console for submission. Other search engines like Bing and Yahoo, also offer webmaster tools for submission.


Search engines operate through three essential tasks: crawling, indexing, and ranking. Crawling involves discovering and fetching web pages, while indexing entails processing and analyzing page content to build an index for quick retrieval. Ranking algorithms then determine the most relevant search results based on user queries.

Ranking is crucial as it determines the visibility of web pages in search results, impacting the amount of traffic they receive. However, websites may have low rankings due to various factors such as difficulties with crawlers, lack of external links, crawler directives blocking search engines, or penalties for spammy practices.

While search engines automatically index websites, manual submission through XML sitemaps can also expedite the process for website inclusion in search results. Google Search Console and other webmaster tools facilitate this submission process for website owners. Understanding the mechanics of search engines and effectively submitting websites can help improve a website’s visibility and ultimately its success in search engine results.