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Term: robots.txt

Definition: Used by websites to communicate with web crawlers and other web robots, robots.txt is a file that provides instructions about which parts of the site to crawl or ignore.

Alternative Names: Robots Exclusion Standard, Robots Exclusion Protocol


Expanded explanation: The robots.txt file is placed in the root directory of a website and uses the Robots Exclusion Standard to guide web robots that are crawling the site. This simple text file tells robots which pages to crawl and which ones not to crawl, thereby helping to control how search engines index the site.

Benefits or importance: The primary benefit of a robots.txt file is its ability to direct the activity of web crawlers, conserving resources on the server. It also enables web administrators to keep certain pages of their website private from web crawlers, if wanted.

Common misconceptions or pitfalls: One misconception is that disallowed pages in the robots.txt file are hidden from the public. This is not true – the robots.txt file is publicly accessible and it only advises compliant web crawlers but does not enforce restrictions.

Use cases: A robots.txt file is essential for large websites that need to guide web crawlers to relevant information and away from irrelevant or duplicate pages. It’s also useful for websites with server limitations as it can help manage the load.

Real-world examples: Here’s an example of a simple robots.txt file:

User-agent: *
Disallow: /private/

This tells all web crawlers not to crawl the ‘private’ directory of the site.

Calculation or formula: There’s no specific formula for a robots.txt file. It’s a simple text file with directives for web crawlers, such as ‘User-agent’ to specify the web crawler and ‘Disallow’ to indicate the paths not to be crawled.

Best practices or tips:

  • Always place your robots.txt file in the root directory of your site.
  • Use the ‘Disallow’ directive wisely, avoiding blocking important pages that should be indexed.
  • Always check your robots.txt file with Google’s Robots Testing Tool.

Limitations or considerations: It’s important to understand that a robots.txt file is advisory and not all web crawlers honour its directives. Moreover, as it’s publicly viewable, it shouldn’t be used for securing sensitive information.

Comparisons: Compared to other methods of controlling crawlers, like meta tags or headers, robots.txt is a more comprehensive and centralised solution. It operates at a site level, not at a page level.

Historical context or development: The Robots Exclusion Protocol was developed in 1994 as a standard to help website administrators control web crawler traffic on their sites.

Resources for further learning:

Related services:

Related terms: User-agent, Disallow, Allow, Crawl-delay, Sitemap, Web crawler, Indexing, SEO, Robots Exclusion Protocol, Googlebot.