A robots.txt file is optional. Google and other search engines will crawl your site whether you have one or not. The file exists to give directives—mostly to prevent crawlers from wasting resources on pages you don't want indexed or analyzed, like /wp-admin/, /cart/, or filtered product views that create duplicate content. Most sites benefit from a basic robots.txt that blocks admin paths, thankyou pages, internal search results, and any staging or dev subdomains. For example, blocking /wp-admin/ on WordPress or /checkout/ on Shopify keeps Googlebot focused on pages that actually matter for rankings. You can also use it to point crawlers to your XML sitemap, though that's more of a convenience than a requirement. That said, robots.txt is not a security tool. Blocking a URL in robots.txt doesn't stop it from appearing in search results if someone links to it, and anyone can read your robots.txt file by visiting yoursite.com/robots.txt. If a page truly needs to stay out of Google, use a noindex meta tag or require authentication. Common mistakes: disallowing your entire site with "Disallow: /", blocking CSS or JavaScript files that Google needs to render pages properly, or assuming robots.txt prevents indexing when it only discourages crawling. We see this a lot when clients accidentally block their whole site during a migration and wonder why traffic tanked. At Ottawa SEO, we create a robots.txt for every client site during technical audits, even if it only contains a sitemap reference and a single disallow rule. It signals that someone's managing the crawl budget intentionally. For smaller sites under 500 pages, the impact is minimal. For larger catalogs or database-driven sites generating thousands of parameter URLs, a well-tuned robots.txt can meaningfully reduce server load and help Google focus on your best content. Bottom line: if you run a simple five-page brochure site, you can skip it. If you have any CMS, ecommerce platform, or user-generated content, set one up. It takes five minutes and prevents future headaches.