Search engines need to discover and crawl pages before they can decide how those pages should appear in search results. Understanding how crawlers access your website is an important part of technical SEO.

A robots.txt file is a plain-text file that communicates crawling instructions to participating search engine bots. When configured correctly, it can help crawlers avoid requesting certain sections of a website that do not need to be crawled.

1. What Is a Robots.txt File?

Robots.txt follows the Robots Exclusion Protocol. It allows website owners to specify which paths participating crawlers may or may not request. The file is normally placed in the root directory of a website.

https://example.com/robots.txt

A file located at https://example.com/blog/robots.txt does not replace the standard root-level robots.txt file for the host.

2. Why Is Robots.txt Important?

Robots.txt gives you a way to manage crawling instructions for supported search engine bots. It can be particularly useful on websites with many URLs, internal search pages, or sections that do not need to be crawled.

• Manage crawling: Set rules for selected URL paths.
• Reduce unnecessary requests: Help crawlers avoid selected URL patterns.
• Support technical SEO: Coordinate crawling rules with your sitemap and indexing strategy.
• Handle large websites: Manage crawl access to areas that generate many URLs.
• Communicate crawler preferences: Maintain readable, centralized rules for participating bots.

A robots.txt file is not a direct ranking improvement. Incorrect rules can prevent search engines from accessing important pages, so each directive should be reviewed before publication.

3. How Does Robots.txt Work?

A crawler can request your robots.txt file before visiting URLs on your website. It reads the rules applicable to its user-agent and checks whether the requested paths match those rules.

1. The crawler requests the root-level robots.txt file.
2. It identifies the applicable user-agent group.
3. It evaluates the requested URL against the relevant rules.
4. It follows the rules according to its implementation.

Different crawlers may support different syntax. Check the documentation of the search engines and bots that matter to your website.

4. Common Robots.txt Directives

These are some of the most commonly used robots.txt directives and symbols.

Google supports path matching, including certain wildcard patterns and the $ end-of-URL marker. Other crawlers may behave differently, so do not assume every bot supports every extension.

5. A Basic Robots.txt Example

The following example allows crawling by default and advertises the website's XML sitemap.

User-agent: *

Sitemap: https://example.com/sitemap.xml

Replace the example domain with your actual domain and ensure the sitemap URL is correct. Crawling is generally allowed by default when no matching disallow rule exists.

6. How to Block Specific Website Sections

You can use Disallow rules to request that participating crawlers avoid selected sections.

User-agent: *
Disallow: /admin/
Disallow: /internal-search/

Sitemap: https://example.com/sitemap.xml

These rules request that matching crawlers avoid URLs under /admin/ and /internal-search/. They do not stop people from opening these URLs or prevent unauthorized bots from accessing them.

7. What Is a User-Agent?

The User-agent directive identifies the crawler for which a group of rules is intended. The asterisk * is commonly used to target all crawlers that follow the standard.

Rules for all crawlers

User-agent: *
Disallow: /private/

Rules for Googlebot

User-agent: Googlebot
Disallow: /temporary/

When a crawler matches a specific group, it may use that group instead of the wildcard group. Check the target crawler's documentation before combining multiple groups or assuming rules will be merged.

8. Adding a Sitemap to Robots.txt

An XML sitemap helps search engines discover URLs that you want them to consider. Adding the absolute sitemap URL to robots.txt is a convenient way to advertise it.

Sitemap: https://example.com/sitemap.xml

Use your real sitemap URL and verify that it is accessible. Listing a sitemap does not guarantee that all its URLs will be crawled or indexed.

9. Robots.txt vs. Noindex

Robots.txt controls crawling, while a noindex directive tells supported search engines not to include an accessible page in their search index.

If you want an accessible page excluded from search results, allow crawling so the crawler can see its noindex instruction. Blocking that page in robots.txt may prevent the instruction from being discovered.

10. Common Robots.txt Mistakes

Blocking the entire website unintentionally

User-agent: *
Disallow: /

This rule requests that matching crawlers avoid every path on the site. If accidentally published, it can interfere with crawling of important pages.

Trying to hide private information

A blocked URL can still be discovered through external links or other sources. Protect sensitive content using authentication and server-side access controls.

Using the wrong file location

Publish the standard file at the root of the relevant host, for example https://example.com/robots.txt. Each subdomain can have its own robots.txt file.

Forgetting to check your rules

A typo or broad rule may block pages you intended to make accessible. Test important URLs and verify the published file after each significant change.

11. How to Create a Robots.txt File

You can write a robots.txt file manually or use an online generator to prepare your initial directives.

1. Identify which crawlers you want to provide instructions for.
2. Decide which URL paths should be crawled or avoided.
3. Write the relevant user-agent and disallow rules.
4. Add your sitemap URL if an XML sitemap is available.
5. Review your rules to ensure important public pages are not unintentionally blocked.
6. Save the file as plain text named robots.txt.
7. Upload it to the root directory of the relevant website host.
8. Open the published URL and test your rules using available crawler tools.

12. How to Test Your Robots.txt File

After uploading the file, open its URL in a browser to confirm that the published text is correct and available. Then review your directives against the intended crawling behavior.

• Confirm the file is available at /robots.txt.
• Check for unexpected Disallow rules.
• Verify that the sitemap URL is valid.
• Use available Google Search Console inspection and robots.txt testing features where applicable.
• Review server logs if you need to investigate actual crawler requests.

A successful browser request does not prove that every crawler interprets the rules identically. Consult the relevant crawler documentation and test important paths.

13. Frequently Asked Questions