The short answer: Google does not care whether you choose www.yoursite.com or yoursite.com. What Google does care about is that you pick exactly one and permanently 301 redirect the other. Allowing both to resolve independently splits your backlinks and leads to duplicate content penalties.
Does WWW or Root Non-WWW Rank Better?
Neither has an inherent SEO advantage over the other. Both are fully capable of achieving #1 rankings across search engines. Brands like Apple, Wikipedia, and Google use WWW. Brands like Twitter, GitHub, and Basecamp use the apex root domain.
What Happens If Both Versions Load Independently?
If typing example.com loads your homepage with an HTTP 200, and typing www.example.com also loads the homepage with an HTTP 200, search engines treat them as two completely separate competing websites:
- Half of the external websites linking to you link to
example.com; the other half link towww.example.com. Your PageRank authority is cut in half. - Search engines index identical page content across two separate hostnames, diluting keyword relevance.
The 4-Way Canonical Redirect Matrix
Every modern website exists in four potential variations:
http://example.com(Insecure Root)http://www.example.com(Insecure WWW)https://example.com(Secure Root)https://www.example.com(Secure WWW)
Your goal: Exactly one of these must return an HTTP 200 OK (your chosen canonical version). The remaining three must immediately return a 301 redirect pointing to that chosen version.
Technical Factor: DNS & CNAME Flattening
While SEO impact is identical, there is one technical difference:
Under original DNS RFC specifications, the apex root domain (example.com) cannot possess a CNAME record; it must use an A record pointing directly to static IP addresses. A www subdomain, however, can easily point to a CNAME (making it easier to integrate with CDNs like AWS CloudFront or Fastly).
Note: Modern DNS providers like Cloudflare and Route53 offer "CNAME Flattening" or "ALIAS" records, which largely eliminates this historical limitation.