We encounter them constantly, though we may not be aware of them. Crawlers, or indexing robots, are responsible for collecting information about web pages, structures, and content. They operate using HTTP and HTTPS protocols, as well as algorithms and rules that determine how and how often they should crawl websites.
A crawler, as a search engine robot, is a useful tool that aids in the SEO of a website. Translated into Polish, it means a caterpillar, but it is also called a spider, robot, bot, or creeper.
Crawler – how it works
The crawler's job is to collect and store descriptive data about a website, known as meta tags . The crawler then indexes them so that the search engine can scan them and extract keywords.
The data obtained by the bot includes both the entire website content and external and internal links.
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The main tasks of an indexing crawler include:
- examination of the website content,
- visiting links on the landing page,
- checking the website code,
- collecting information about the website,
- checking for content updates.
All these activities affect the visibility of a website in a given search engine.
Google Crawler and its role in the search engine
Googlebot is Google's crawler. By analyzing the code and structure of a page, the crawler gathers information about its content, accuracy, and usefulness.
This data is then stored by the search engine and used to properly tailor a list of websites in response to the user's query.
The crawler evaluates the similarity of the content on each previously indexed page with the search term entered into the search engine and, based on this, decides which websites will appear first in Google.
The crawler therefore has a huge impact on a page's visibility in search results . Furthermore, thanks to indexing and data collection, the search engine maintains a comprehensive and updated database, providing users with verified and useful information.
How does a crawler index web pages?
We already know that these bots operate by scanning websites , but it's worth mentioning that not every website performs the same way. The difference is primarily related to the content of a given page and the number of changes made to it.
For example, if a detailed analysis of the entire website is necessary – its structure, source code, or any duplicate content – then we are dealing with the so-called deep crawl method.
However, for pages where data is frequently updated, the bot will only perform a fresh crawl . This means that it will only check new, changed areas, without repeating the indexing of previously existing content.
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Does the crawler have access to all page content?
Before a crawler can begin its work, it must download a file called "robots.txt" which contains detailed instructions for the crawler, specifying which documents from the website can be crawled and which addresses are not accessible to it.
From the very beginning, robots must check whether they have access to the content located in the selected area of the page.
This is determined by the entry in the robots.txt file:
- Allow: / – means that the robot has full access to the page,
- Disallow: / – completely blocks access to bots,
- It is also possible to enter an entry Disallow: / only for specific subpages – then other areas can be viewed.
Content Verification and Indexing
It's worth noting that metadata indexing occurs after review and can be blocked. Even if a crawler analyzes the content on a selected website, it isn't always authorized to display it in search results.
For example, if the meta section contains the entry "noindex" or "none", the robot can only view the content but is not allowed to make it available to users.
The crawler derives its knowledge of the list of addresses from the sitemap.xml file and links. However, if we want to submit a given URL to the crawler ourselves, we can do so using the Google Search Console tool.
Google Crawler and other robots
Each search engine has its own indexing bot. These include:
- Googlebot – a web robot used by Google,
- Bingbot – Bing search engine crawler,
- Yandex bot – creates the database of the Yandex search engine.
However, the use of indexing bots is not limited to search engines – they are also used for other activities related to websites.
Crawlers and their purpose
There are crawlers designed for, among other things:
- website content analysis that improves SEO activities, e.g. Screaming Frog or SEMrush,
- e-commerce that analyzes online stores and products, eg. eBay Crawler or Amazon Crawler.
Using bots, we can monitor changes on pages, add comments, analyze links, and create contact databases. Depending on user needs, they can be programmed to perform specific tasks.
Google Crawler and SEO
SEO website optimization involves adapting the website to search engine algorithms, thereby increasing its visibility.
Google bots can be of great help in this matter, as they determine the website's position in the search results for a given query.
Google Crawler affects, among others:
- identifying technical errors, e.g. broken links or duplicate content,
- assessment of the correctness of the structure of a given page and the value of the content,
- increasing visibility in organic search results,
- increase in the popularity of the site in the ranking, which is caused by the analysis of external links.
Following the guidelines according to which Google Crawler evaluates and classifies websites will contribute to better website positioning and, consequently, to increased interest from potential customers.
Summary
The above article covers the following topics:
- Crawlers are robots that collect and index data about websites, which allows search engines to analyze their content and decide their visibility in search results.
- Googlebot analyzes the content and code of web pages, collecting the data necessary to properly index them and determine their position in search results in response to user queries.
- Crawler indexes pages using the method deep crawl for a complete analysis of the website structure and code or fresh crawl to quickly check only newly added and updated content.
- The crawler accesses selected website content based on instructions contained in the file robots.txt, which using commands Allow i Disallow indicates to him which areas or subpages he can search and which are blocked to him.
- Even if a crawler analyzes the page's content, it can be blocked from appearing in search results using "noindex" tags, and it primarily finds new URLs through sitemap.xml files, links, or Google Search Console submissions.
- Each search engine, such as Google, Bing, or Yandex, has its own dedicated indexing bot, although crawlers are also used in many other processes related to website analysis.
- Specialized crawlers enable precise SEO analysis and e-commerce monitoring, and adapting your website to Googlebot guidelines allows you to eliminate technical errors and effectively improve your website's position in search results.
