Which is better for SEO - a redirect to www.example.com or just example.com?

Question

Search Engine Optimization

I notice that many SEO companies use www.

Answer 1

SEOs don't care which domain to promote.

Answer 2

No difference.
It is important to decide on one single version and, on the other hand, put a 301 redirect to the main one.
+ write Host directive in robots.txt