What is Robots.txt file

The robots.txt file is a simple text file that resides in the root directory of a website (e.g., https://www.example.com/robots.txt). It provides instructions to search engine crawlers (also known as "robots" or "bots") about which parts of the website they are allowed or disallowed from crawling and indexing. By using the robots.txt file, you can control crawler access to specific sections of your site, optimizing search engine efficiency and avoiding unwanted content from being indexed.

Why Robots.txt is essential for your site

The robots.txt file is essential for your site because it allows you to manage and control search engine crawlers' access, optimizing your website's performance and visibility. Here are several key reasons why robots.txt is important:

Prevents Crawling of Sensitive or Non-Public Content

robots.txt helps block access to pages or directories containing sensitive data (e.g., admin pages, private user files, internal data).

By disallowing these areas, you ensure that search engines don’t accidentally index pages that should remain private.

User-agent: *

Disallow: /admin/

Reduces Server Load and Bandwidth Usage

Controlling which pages bots can access can reduce unnecessary crawling, lowering server load, which is particularly important for large sites or sites with limited server resources.

This way, crawlers focus on your most important pages, which is especially useful for sites with dynamically generated pages that might overwhelm server resources if crawled extensively.

Improves Crawl Efficiency and SEO

Search engines have a “crawl budget,” or a limited number of pages they can crawl on your site within a specific time frame. Blocking irrelevant or redundant pages (like duplicate content or archives) frees up the crawl budget for more important content.

User-agent:*

Disallow: /?sessionid=

Prevents Indexing of Low-Value or Duplicate Pages

If your site generates URLs with duplicate or low-value content (like printer-friendly versions, filtered pages, or staging environments), robots.txt can prevent crawlers from accessing them. This reduces the chances of duplicate content issues that can harm your SEO.

User-agent: *

Disallow: /print/

Controls Staging and Development Environments

During website development, robots.txt can restrict access to staging or development environments to prevent them from being indexed before going live.

User-agent: *

Disallow: /

Provides Guidance to Specific Crawlers

You can specify directives for different search engine crawlers, tailoring access based on the importance of specific bots or the content relevant to them. This is useful if you want Googlebot to access different sections than a bot from a less relevant search engine.

User-agent: Googlebot

Disallow: /

Supports Compliance with Legal or Privacy Requirements

robots.txt can help comply with legal or privacy requirements by blocking access to personal data, GDPR-sensitive areas, or files that are not intended for public access.

How to create a correct Robots.txt file

To create a robots.txt file, use a simple text editor like Notepad, TextEdit, or emacs. Avoid word processors as they may save files in formats that add unexpected characters, like curly quotes, which can disrupt crawler functions.

When saving, select UTF-8 encoding if prompted.

Format and Location Guidelines

1. File Naming and Count:

   • The file must be named robots.txt.

   • Each site can have only one robots.txt file.

2. File Location:

   • Place the robots.txt file in the root directory of the site it applies to. For example, to manage crawling for URLs under https://www.example.com/, the file must be located at https://www.example.com/robots.txt.

   • Subdirectory placements, like https://example.com/pages/robots.txt, are invalid. If access to the site root is restricted, use meta tags as an alternative.

   • You can create separate robots.txt files for subdomains (e.g., https://site.example.com/robots.txt) or host it on non-standard ports (e.g., https://example.com:8181/robots.txt).

3. File Encoding:

   • Save the robots.txt file as a UTF-8 encoded text file (this includes ASCII). Characters outside the UTF-8 range may be ignored by Google, potentially invalidating the rules in the file.

   
   
   
   

Guidelines for Adding Rules to Your robots.txt File

A robots.txt file provides instructions for web crawlers on which sections of your site can be accessed. Follow these guidelines when adding rules:

1. Structure and Grouping:

   • A robots.txt file contains one or more groups of rules.

   • Each group consists of multiple rules (directives) with one rule per line.

   • Each group starts with a User-agent line specifying the targeted crawler.

2. Group Content:

   • User-agent: Specifies which crawler (or user agent) the rules apply to.

   • Allow: Indicates directories or files the agent is permitted to crawl.

   • Disallow: Lists directories or files the agent is restricted from crawling.

3. Processing Order and Rule Matching:

   • Crawlers read groups from top to bottom.

   • A user agent will follow only the first, most specific group that matches it. If there are multiple groups for the same agent, they will be combined into one group before processing.

   • By default, any page or directory not blocked by a Disallow rule is accessible to crawlers.

4. Case Sensitivity:

   • Rules are case-sensitive. For example, Disallow: /file.asp applies to https://www.example.com/file.asp but not to https://www.example.com/FILE.asp.

5. Comments:

   • Use the # character to add comments. Anything following # will be ignored by crawlers.

   
   
   
   

Here's an example of a robots.txt file and an explanation of each part:

User-agent: Googlebot

Disallow: /private/

Allow: /private/public-info.html

• User-agent: This specifies the crawler that the rule applies to—in this case, Googlebot (Google’s web crawler).

• Disallow: /private/: This rule blocks Googlebot from accessing all content under the /private/ directory.

• Allow: /private/public-info.html: Even though the /private/ directory is blocked, this specific page (/private/public-info.html) within that directory is accessible to Googlebot. The Allow rule is more specific than the Disallow, so it takes precedence here.

Understanding the Limitations of robots.txt

Before creating or editing a robots.txt file, it’s essential to understand its limitations. In some cases, you may need additional methods to prevent URLs from being found or indexed on the web.

1. Not Supported by All Crawlers:

   • While reputable search engines like Google, Bing, and others respect robots.txt rules, some crawlers ignore them. This means robots.txt cannot enforce blocking; compliance depends on the crawler.

   • For secure information, use more reliable blocking methods, such as password-protecting files or directories.

2. Crawlers Interpret Rules Differently:

   • Even though reputable crawlers follow robots.txt rules, each one may interpret syntax in its own way. Knowing the correct syntax for different crawlers is crucial since some may not understand certain instructions.

3. Disallowed URLs Can Still Be Indexed:

   • Pages blocked by robots.txt may still be indexed if linked to from other websites. While Google will not crawl the content, it can still add the URL and link text to its index if it’s publicly linked elsewhere.

   • For complete removal from search results, use stronger methods like noindex meta tags, HTTP response headers, password protection, or deleting the page.

   
   

In summary, it is important to note that while robots.txt is useful for controlling crawler access, it doesn’t fully prevent content from being indexed or accessed. For sensitive or private data, use additional blocking techniques for full security.