What is robots.txt used for?

Started by danielnash, 03-08-2016, 22:25:58

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danielnashTopic starter

I learnt here about sitemap.xml file. Now I'm little bit confused for what is robots.txt used for?

Please guys clear it.


hoahoa1909

-Non-image files
For non-image files (that is, web pages) robots.txt should only be used to control crawling traffic, typically because you don't want your server to be overwhelmed by Google's crawler or to waste crawl budget crawling unimportant or similar pages on your site. You should not use robots.txt as a means to hide your web pages from Google Search results. This is because other pages might point to your page, and your page could get indexed that way, avoiding the robots.txt file. If you want to block your page from search results, use another method such as password protection or index tags or directives.

-Image files
robots.txt does prevent image files from appearing in Google search results. (However it does not prevent other pages or users from linking to your image.)

-Resource files
You can use robots.txt to block resource files such as unimportant image, script, or style files if you think that pages loaded without these resources will not be significantly affected by the loss. However, if the absence of these resources make the page harder to understand for Google's crawler, you should not block them, or else Google won't do a good job of analyzing your pages that depend on those resources.


Nimit.Suri

The robots.txt file is a simple text file placed on your web server which tells webcrawlers like Googlebot if they should access a file or not
Improper usage of the robots.txt file can hurt your ranking
The robots.txt file controls how search engine spiders see and interact with your webpages.The first thing a search engine spider like Googlebot looks at when it is visiting a page is the robots.txt file.It does this because it wants to know if it has permission to access that page or file. If the robots.txt file says it can enter, the search engine spider then continues on to the page files.

Hope this helps
  •  

RH-Calvin

Robots.txt is a text file that is used to insert in your website to contain instructions for search engine spiders. The file lists webpages that are allowed and disallowed from search engine crawling. They help to control the crawling activity on your website.

carldweb

#4
The robots.txt file is a critical tool in SEO (Search Engine Optimization) and overall website management. It's used to instruct web robots, such as search engine bots, which parts of a site they should or shouldn't access. This file is typically placed at the root of a website.

The robots.txt protocol, also known as the Robots Exclusion Standard, not only allows you to control where search engine crawlers go but also can prevent them from pulling certain pages onto their servers, something that can be valuable if you don't want a search engine to index certain pages (e.g., pages with sensitive information or pages with duplicate content).

Here's the basic structure of a robots.txt file:

User-agent: [user-agent name]
Disallow: [the URL path you want to disallow]
Allow: [the URL path you want to allow]

User-agent specifies the search engine bot to which the rule applies. Use * to apply the rule to all bots.

Disallow tells the bot not to crawl or index a certain part of your site. For example, Disallow: /private/ would prevent bots from crawling or indexing anything in the /private directory of your site.

Allow instructs the bot that it can access a certain page or area of the site. This is typically used to make exceptions to broader Disallow rules.

It's important to note that the instructions in the robots.txt file are purely directives and respectful bots will follow these rules. Some may ignore them, like certain malware bots, which look for vulnerabilities on websites.

This is how a sample 'robots.txt' file might look:

User-agent: *
Disallow: /private/
Disallow: /cgi-bin/

User-agent: Googlebot
Allow: /special-google-directory/
In this sample:

The first set of rules applies to all bots (User-agent: *) and instructs them not to crawl or index the /private/ or /cgi-bin/ directories.
The second set of rules applies specifically to Google's bot (User-agent: Googlebot) and instructs it that it can access the /special-google-directory/.
Another feature you can utilize in your robots.txt file is the "Sitemap" directive which enables you to specify the location of your XML sitemaps:

Sitemap: https://www.yourwebsite.com/sitemap.xml
By putting this line in your robots.txt file, you are making it easier for search engine crawlers to locate and use your sitemap.

Lastly, although robots.txt file is powerful, it's also delicate. A small error can result in blocking search engines from crawling and indexing your site, so always be careful when setting up or changing your robots.txt file.

let's cover the topic of robots.txt more deeply:

Regular vs Crawl-delay directives

Some search engines allow the "Crawl-Delay" directives, although they are not officially part of the Robots Exclusion Protocol. This command specifies how many seconds a crawler should wait between successive actions. This delay helps prevent a server from being overwhelmed by requests.

For instance:

User-agent: *
Crawl-delay: 10
In this snippet, the webmaster requests all robots to wait 10 seconds between requests. Keep in mind that this isn't honored by all crawlers.

Wildcards

The Robots Exclusion Protocol doesn't officially support wildcards (*), but they are recognized by several search engine bots including Google. For example:

User-agent: *
Disallow: /*.gif$
In this case, all robots are requested not to crawl or index .gif files on the site.

Comments

Anything following the # on a line in the robots.txt file is considered a comment and will be ignored by bots. This can be useful for making notes to yourself or others about why a certain rule is in place. For instance:

User-agent: *
Disallow: /private/ # Don't allow bots in private directory
Disallow: /cgi-bin/ # No bot should index these scripts
Testing and validating

Test your robots.txt file to make sure it behaves as you expect. Google provides a robots.txt Tester in Search Console. This tool allows you to submit and test a robots.txt file to see if it has the intended results. Also, other validation tools are available online to help ensure your file is properly formatted.

Keep in mind

Remember, not all bots will respect the robots.txt file. While legitimate search engine spiders usually adhere to the rules, malicious robots may completely ignore the file. So don't rely on robots.txt to secure sensitive parts of your site. Instead, use proper server-based security measures e.g. password protections or IP address restrictions.

Finally, misuse of the robots.txt file can lead to severe consequences. An incorrectly formatted or located file might not be read correctly by search engine bots, leading to crawling and indexing issues. If you disallow the wrong pages or sections, you could prevent search engines from accessing and indexing important parts of your site, potentially leading to drops in organic traffic. Therefore, be very careful and thorough when editing this file.


There are many aspects in terms of the robots.txt file that have been covered, but here's more about some advanced uses and considerations:

Multiple User-agent Lines

If you want sections of your site to be treated differently by different robots, you can define multiple user-agent groups, like so:

User-agent: googlebot
Disallow: /private-to-googlebot/

User-agent: bingbot
Disallow: /private-to-bingbot/

User-agent: *
Disallow: /private-to-all-bots/
In this case, each bot will consider only the group that matches its user-agent name and the default *. So, for example, Googlebot would ignore the bingbot rules and vice versa.

Disallow vs Noindex

Just because a page is allowed to be crawled via robots.txt doesn't mean it will be included in the search engines' indexes. Inversely, just because a page is marked as Disallow in robots.txt, search engines could still decide to index the page (for instance, if other pages that are allowed to be indexed link to it).

If you want a page not to be indexed at all, you need to use a different method: the noindex directive in a page's meta tag (contained within the <head></head> tags of your HTML). However, in order for a search engine bot to see this noindex tag, the page must not be disallowed in the robots.txt. It's a catch-22—you want the bot to access the page to read the noindex directive, but by accessing the page, the bot might index it.

If you use both Disallow in robots.txt, and a noindex meta tag on the page, search engine bots that obey robots.txt will never see the noindex tag. To avoid confusion about what's indexed and what's not, don't mix Disallow and noindex.

Clean and Structured Setup

For readability and easy management, keep your robots.txt well structured and clean. Group all Disallow entries under one User-agent, rather than repeating the same User-agent with different Disallow entries.

Handling URL parameters

If you have URL parameters that show the same content and cause duplicate content issues (e.g., sorting parameters on e-commerce sites), you could disallow crawling of URLs with these parameters in the robots.txt file.

Here's an example that disallows any URLs that contain the parameter sortorder:

User-agent: *
Disallow: /*?*sortorder=
Updates

Over time, your site evolves. Sections are added or removed, pages come and go, and changes are made to better align your site with your mission. Regular reviews (at least once a year, if not more) of your robots.txt file are crucial to maintaining the health, visibility, and user experience of your website.


Here are some additional deep facts and considerations about robots.txt:

Long Delay Times

If you choose to include a Crawl-delay directive, be cautious about setting it too high. A delay of several seconds could severely limit how much of your site gets crawled. With billions of websites on the web, a crawler simply can't afford to wait 10 or 20 seconds between requests. If you discover that search engines are heavy users of your server resources, you might be better off optimizing your website's performance.

Non-standard directives

Some search engines support directives beyond the standard Disallow and Allow. For instance, Google supports Host, which lets you specify the preferred domain for a site with multiple domains or subdomains. Please note that these are generally non-standard, engine-specific extensions that not every bot will understand or obey. Always refer to the specific search engine's official documentation when using these directives.

Sitemap

You can specify the location of your website's sitemap in your robots.txt file, helping search engines find and crawl all your pages. Ensure your Sitemap is up to date and lists all pages your want to be indexed:

Sitemap: http://example.com/sitemap_location.xml
Order of precedence

Rules in robots.txt are typically processed from top-to-bottom with the most specific rules taking precedence. For example, if you have:

User-agent: *
Disallow: /

User-agent: googlebot
Disallow:
Here, googlebot is allowed to crawl all areas because the specific rule for googlebot overrides the general Disallow: / for *.

Understanding the limitations

Use of the robots.txt doesn't guarantee that a page won't appear in search results. If external sites are linking to it, search engines may still index the page. Also, URL data and potentially cached versions of the page might still be available. To prevent a page from being indexed at all, the nofollow, noindex meta tags or X-Robots-Tag HTTP header directives should be used.

The "Allow" directive

While Disallow tells search engines where not to go, Allow can be used to specify URLs that you want to be accessible to web spiders, even if the parent directory has been disallowed. This is only recognized by some web crawlers like Googlebot. Here's an example:

User-agent: *
Disallow: /folder/
Allow: /folder/page.html
In this example, all pages inside /folder/ are blocked except /folder/page.html.

Remember, both the 'Allow' and 'Crawl-delay' directives aren't officially part of the robots exclusion protocol, and the behavior of these might differ across search engines.

Status 404 vs 403 for robots.txt

When a robots.txt is not found, servers return a 404 status. A 404 status for robots.txt is perfectly fine; it means that every page may be crawled. If, however, a server returns a 403 for robots.txt, it means that no pages may be crawled.

So this concludes more advanced instructions and considerations on robots.txt. It's an exceptionally functional tool when dealing with website crawling, but please keep in mind that its guidelines are completely voluntary. Malicious actors will not be deterred if they intend to scrape your site or infect it with malicious software.


jaysh4922

Robots.txt is a text file that is inserted into your website and contains information for search engine robots. The file lists webpages that are allowed and disallowed from search engine crawling.