Under what circumstances would you use a 'noindex' meta tag instead of disallowing a URL in robots.txt?

You would use a 'noindex' meta tag instead of disallowing a URL in robots.txt when you need Googlebot to crawl a page to discover the 'noindex' tag. The robots.txt file prevents crawlers from accessing a page entirely. A 'noindex' meta tag allows crawlers to access the page but instructs them not to include it in Google's index. The key difference is that with robots.txt, the page's content will not be crawled and therefore signals like canonical tags or link equity will not be passed. Use 'noindex' in situations where: 1) You want to prevent a page from being indexed but still want Google to follow links on that page (e.g., to pass link equity to other pages). 2) The page needs to be crawled to discover other directives, such as a canonical tag that points to another page. If a page is blocked by robots.txt, Google will not see the canonical tag. 3) You want to eventually remove the page from the index completely. Google needs to recrawl a page with a 'noindex' tag to process and acknowledge it before removing the page from the search results. If a page is blocked in robots.txt, Google may still show it in search results if it finds the URL through other means, but it won't be able to crawl the page to see a 'noindex' directive.