Google outlines the recommended practices for robots.txt, including when to use robots.txt directives and noindex tags for SEO.

According to Splitt, a Google Developer Advocate, both strategies help control how search engine crawlers interact with a website.
They should not be substituted for one another, though, as they provide distinct functions.
When To Use Noindex
Search engines are instructed not to display a specific page in their search results with the “noindex” directive. The X-Robots HTTP header or the robots meta tag may be used to include this directive in the HTML head section.
When you want to prevent a page from appearing in search results but still let search engines see its content, use “noindex.” This is useful for pages like thank-you pages or internal search result pages that people may view but that you don’t want search engines to show.
When To Use Disallow
The robots.txt file on a website contains the “disallow” command, which prevents search engine crawlers from accessing particular URLs or patterns. Search engines will not crawl or index content from a page that is prohibited.
When you wish to prevent search engines from accessing or processing a page totally, Splitt suggests using “disallow.” This works well for sites that aren’t important to search engines or for sensitive material, such as private user information.
Common Mistakes to Avoid
Using “noindex” and “disallow” on the same page is a standard error website owners make. Splitt cautions against this as it may lead to issues.
Search engines cannot recognize the “noindex” directive in the page’s meta tag or X-Robots header if a page is blocked in the robots.txt file. The page may still be indexed, albeit with less information.

Google offers a robots.txt report in Google Search Console to test and track the impact of robots.txt files on search engine indexing.
Why This Matters
SEO experts must correctly comprehend how to employ the “noindex” and “disallow” directives.
Utilizing the various testing tools and heeding Google’s guidance will help guarantee that your content shows up in search results as intended.
