Extended definition
Text file on your site (at /robots.txt) telling crawlers which pages they can access and which to skip. "Polite" crawlers respect it; it doesn't block actual indexing, just crawler access.
Context and application
Classic confusion: people think Disallow: in robots.txt blocks indexing. NO. Robots.txt only blocks crawl. If a page was already indexed or externally linked, Google can keep it in the index even though it can no longer crawl it. For real de-indexing, you need the noindex tag IN the page — meaning the page has to remain crawlable for Google to read the tag. Sounds paradoxical, but that’s how it works.
In practice
if you want a page not indexed, you use the noindex tag, NOT robots.txt.
How SEO Master PRO MAX helps
For Robots.txt, the relevant module in the app is Audit module. See the dedicated page for how it works concretely on your site.
See Audit module →Related terms
Sitemap, Noindex, Indexing.