domain name with www & without www.

[stephen86]

Recently i m headache with the issue of domain name with www & without www.I have done much study but still feel confuse so , i hope i can get help here.

1st i would like to know what's the difference between the domain name with www & without www
as i saw some website had redirected one of it (e.g.www.xyz.com to xyz.com) but some website keep both work.
So may i know ,in terms of SEO , which practise better ?

2nd ,when i check the inlinks by google link operator and yahoo site explorer , the result is confusing me again .
For google , it showed same result for the domain with www and without www. But yahoo site explorer showed a Big difference result,so may i know how it could be ?
Is it due to Yahoo treats the domain with www and without www as a different sites?

[beu]

Don't worry stephen86 you aren't alone.

Technically www.xyz.com is different than xyz.com. Having the same content available at both URL versions will causes Google and/or other engines to pick one URL or the other (canonicalize a URL). Engines may not always pick the "best one" so in order to help engines make the right choice it's best to redirect the least favored URL via 301 redirect to the favored version of the URL.

[stephen86]

Thanks for your answer.
So,is it google treat the page with www and without www same but yahoo treat it as difference?

[felisha]

I agree with beu. Choose one URL version, www or nonwww, since google may consider them as duplicate content especially when both versions are indexed, this may create a problem to your site. All your links also must use the URL version you preferred so that all link juices will be targeted to the version you are optimizing.