Your robots.txt file sits at the root of your domain—never in a subdirectory. For example, if your site is example.com, the file is always at example.com/robots.txt. This isn't optional; search engine crawlers specifically look for it at that exact URL, and nowhere else. To check if you have one, type your domain followed by /robots.txt into any browser. If the file exists, you'll see its contents as plain text. If you get a 404 error, you don't have a robots.txt file, which is fine—it's not mandatory. Most platforms like WordPress, Shopify, and Wix generate one automatically, though the contents vary. If you're running WordPress, you likely won't find a physical robots.txt file in your root directory via FTP. WordPress generates a virtual one on the fly unless you upload a physical file to override it. To check what WordPress is serving, just visit yoursite.com/robots.txt. If you need to customize it, you can use a plugin like Yoast SEO or upload a custom robots.txt file directly to your root folder via FTP or your hosting file manager. For other platforms: Shopify serves a default robots.txt that you can partially customize through theme templates. Wix handles it automatically with limited control. Custom-built sites require you or your developer to create and upload the file manually to the web root. At Ottawa SEO, we audit the robots.txt file early in every technical SEO project. Common mistakes include accidentally blocking important pages with "Disallow: /" or blocking CSS and JavaScript files that Google needs to render pages properly. We also check for conflicting directives and whether the sitemap URL is declared—adding "Sitemap: https://yoursite.com/sitemap.xml" helps crawlers find your sitemap faster. If you manage multiple subdomains, each needs its own robots.txt. The file at example.com/robots.txt doesn't apply to shop.example.com—you'd need shop.example.com/robots.txt separately. Same rule applies to HTTPS versus HTTP; they're treated as different hosts, though most sites redirect one to the other anyway.