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What is a search robot
A search robot, also known as a web crawler or web spider, is a specialized program that autonomously explores web pages and transmits the collected data to search engines or website owners. The most well-known users of such crawlers are search engines, which use them to navigate through available links, analyze the content of pages on the internet, and update their databases.
Crawlers are not limited to just HTML pages—they can also scan documents in various formats, including PDF, Excel, PowerPoint, and Word. This enables them to gather more comprehensive information about the content available on the web.
Why is a search robot needed
Search robots play a key role in the functioning of search engines, serving as a link between published content and users. If a page has not been crawled and added to the search engine's database, it will not appear in search results, and access to it will only be possible through a direct link.
Moreover, robots affect the ranking of pages. For instance, if a search robot cannot properly crawl a site due to unknown APIs or JavaScript functions, it may result in error pages being sent to the server, while some content remains unnoticed. Since search engines use special algorithms to process the received data, such pages may end up at the bottom of search results.
How a search robot works
Before a site or file can be added to a search engine's database, the search robot needs to discover it. This usually happens automatically when it follows links from already known pages. For example, if a new post appears in a blog, the crawler notes this and adds the post to the schedule for the next crawl.
If the site has a sitemap.xml file, the crawler reads links from it for scanning during each update. It is also possible to manually submit a specific URL for crawling by connecting the site to services such as Yandex.Webmaster or Google Search Console.
When a page is accessible, its scanning begins: the crawler reads the text content, tags, and hyperlinks, then uploads the data to the server for processing. The data is then cleaned of unnecessary HTML tags and structured before being placed into the search engine's index. The speed of indexing varies among different search engines—for example, Yandex may add new pages within a few days, while Google does this within a few hours.
Types of robots
The most well-known web spiders belong to search engines and are responsible for adding and updating data in search results. Each system has specialized robots that deal with specific types of content. For instance, Google has Googlebot-Image for images, Googlebot-Video for videos, and Googlebot-News for news. Yandex also uses separate spiders for its services, such as Market and Analytics, and has a main and fast robot called Orange.
It's important to note that standard indexing of pages can take anywhere from several days to weeks; however, there are accelerated processes that allow fresh content to be added to search results almost instantly. Nonetheless, only a limited number of resources can undergo such rapid indexing.
Problems that may arise when working with search robots
Despite the important role that search robots play, they can encounter a number of problems. First, incomplete and slow indexing may be caused by a complex site structure or a lack of internal linking. This complicates full crawling and can take months.
Secondly, high server loads from frequent crawls may lead to website malfunctions. Although search engines have their own schedules and limitations, sharp traffic spikes caused by mass page additions can negatively affect the availability of the resource.
Additionally, it's worth mentioning the risks of information leakage. If access to pages is not restricted, search robots may accidentally index materials that are not intended for public access, potentially leading to breaches of confidential data.
How to influence the work of robots
To improve the crawling speed and quality of indexing, it is important to eliminate technical issues on the site, such as hosting errors and duplicate pages. This will increase the chances of quick indexing. It is also recommended to implement web analytics systems, such as Google Analytics or Yandex.Metrica, and connect the site to tools like Google Search Console and Yandex.Webmaster.
Furthermore, creating a sitemap.xml file and properly configuring the robots.txt file will help search robots better navigate the site. It is important to report new sections and pages by adding them to the sitemap and using priority and changefreq tags to indicate the frequency of content updates.