How Search Engines Work: Crawling, Indexing, and Ranking
In a nutshell, search engines function by crawling the web using bots called spiders. These aptly-called web crawlers follow links across web pages to find new content that they’ll add to the search index. Relevant results are extracted from this search index and ranked based on an algorithm every time you use a search engine. This process makes it imperative for you to understand how search engines work, specifically, how they find, index, and rank content if you want to perform well in search engine results pages.
Before diving any deeper, let’s do a quick brush up on the definition of a search engine:
What are Search Engines?
Search engines are online tools that find and rank web content based on an end user’s search query. Proper search engines consist of two parts:
Search Index – the digital library of information contained in web pages.
Search Algorithm – computer programs that rank relevant results from the search index.
How do Search Engines work?
The primary functions of search engines are as follows:
Search engines comb the Internet for content and check the associated code for each URL they find.
Search engines store and organize the content they find during the crawling stage. A webpage is more likely to be displayed in the relevant results list once it’s indexed.
Finally, search engines indicate the pieces of content that best answer a searcher’s query. The list that appears on the result pages is organized from the most to the least relevant.
Crawling: How Do Search Engines Crawl the Web?
Search engines discover fresh content by sending out web crawlers or spiders to find them. These computer programs or robots search for content, including web pages, videos, images, PDF files, among others, by visiting specified links. Discovering content, even on new websites and pages, is made simple because they can visit these online sites pretty quickly.
When you’re creating content, it’s a good idea to link to it from existing pages on your site or another website to ensure search engines discover it. These crawlers are more likely to visit popular websites that create new content more often than relatively unknown websites. Getting a link from a well-known site can help your content get discovered more quickly.
Another step you can do to help search engines crawl your site is to create a sitemap that links to every page on your website. It’s a good way of letting search engines know that your site is available and ready for crawling, making it a fundamental feature of your overall SEO strategy.
For you to see additional data on the pages that Google has already crawled and errors that may have occurred in the process, signing up for a Google Console account is a great step to take.
Indexing: How Search Engines Read and Store Website Information?
After web crawlers read a particular page, they process every piece of information and submit it in an extensive database called a search index.
This index includes all the discovered URLs, together with relevant key signals pertaining to the content of each URL, including:
- What’s included on the page? The type of content being crawled using microdata, particularly schema.
- What topics does the page cover? The keywords that are uncovered within the content on the page.
- How recently was the page updated? The freshness of the page.
- What are the options available for people to interact with the page? The previous user engagement of the page and the entire domain.
It’s worth noting that each search engine creates its own index of online pages. So, Google doesn’t rely on other indices to generate search results. Each webpage gets an entry, so algorithms of search engines have access to contextual information that one contains.
Through these massive indexes, Google and other search engines are able to locate relevant information within pages quickly and with precision.
Why Might Your Page Not Be Indexed?
Sometimes, a specific URL will not be indexed by a search engine. Several circumstances might cause this, including:
- Search engine algorithms deem your page to have thin content, duplicate content, or low quality overall.
- NoIndex Tag or Canonical Tag — these are directives on your webpage telling search engines not to index the page or to index another page that’s similar.
- The URL returns an error page, such as a 404 Not Found HTTP response code.
- Robots.txt file exclusions — a file that tells search engines what they shouldn’t visit on your website.
Ranking: How Search Engines Rank Websites?
Ranking takes place right after the indexing phase.
When search engines show results to end-users, they’re unable to show all the pages in their search index. Instead, they choose specific pages to display and the particular order in which these listings will appear.
Search engines must use the information from their search index to accurately come up with a list of pages ranked according to relevance.
The seemingly arbitrary and problematic task of ranking sites is made easier by strictly adhering to specific factors that help search engines determine page relevance.
These include two main factors, namely:
Keywords are phrases that end-users key in when performing a search. Search engines will then look for the exact and related keywords while crawling web pages. Google determines where your page ranks based on your page’s keywords and content, among other factors.
Google and other search engines also use backlinks (links that go back to a page on your website coming from another site on the web) to determine the relevance of your content based on the pages that link to it. In particular, they pay attention to the quality and quantity of backlinks to help determine your page’s ranking.
Apart from backlinks and keyword selection, page ranking also involves other factors that focus primarily on user experience, which include:
- Page Load Speed
- Site Security
- Site Usability
Google considers all of these factors when ranking your site using incredibly advanced artificial intelligence that’s more than capable of identifying what users want to see when searching. Further, it can better understand the context of all the words in a search query through machine learning and natural language processing, making understanding misspellings and synonyms a lot easier.
Crawling, Indexing, Ranking: Why Do They Matter
One surprising fact about SEO is that it’s the least popular digital marketing channel. Less than half (about 44%) of the world’s businesses incorporate it into their overall marketing strategy. This statistic is mind-boggling, to say the least, since getting crawled, indexed, and gaining a competitive ranking on search engines are critical to growing a company.
The top reasons why (and how) search engines are vital to your business’s growth are as follows:
Search Engines Help People Discover your Business
When more people discover your business, it becomes more feasible for your company to nurture leads and convert them into sales. Search engines have a 14.6% close rate, 2% more than what traditional marketing channels provide.
SEO helps search engines maintain this impressive close rate because it:
- Helps reach prospective clients when they’re interested in a product or service you offer
- Helps visitors of your site find relevant information that can make converting easier.
- Nurtures leads through every step of the buyer’s journey, from awareness to making a purchase.
Simply put, search engines help you reach your dream clients at the right time with the right content. SEO can spell the difference in capturing more leads, as well as sales and revenue.
Most Buyer Journeys Take Place on Search Engines
The majority of online experiences (at least 90%) begin with search engines. Nowadays, people turn to search engines when performing different tasks, such as finding a new diner, upgrade their equipment, or look for their company’s next big project.
With the buyer’s journey in mind, end-users don’t want to be prospected, demoed, or offered to close a sale when they aren’t ready to buy. However, with the help of SEO, search engines can still help those looking for additional information about your product. This will prove pivotal in the buying decision of your clients later on.
Search Engines Keep your Business and its Target Audience Connected Around the Clock
Prospective clients make searches 24/7. For this reason, search engines make for excellent team members. By utilizing SEO, your business captures valuable traffic without costing you anything for overtime.
With a sound SEO strategy in place, your website serves as a hub for potential customers to learn about your business, contact you directly, and — if you’re maintaining an eCommerce site, purchase your products.
Google and other search engines utilize web crawlers to find sites to add to their search index. Most sites listed on search engine results pages aren’t manually submitted but are added automatically once web crawlers crawl the web.
To summarize how search engines work: web searches work in three stages: crawling, indexing, and ranking. Inclusion in search results is straightforward and doesn’t cost a dime nor require you to submit your site for consideration.