What is the different between http://www.example and http://example.com

[idandone]

Hi Guys,
What is the different between http://www.example.com and http://example.com?
I'm looking for technical explanation and also want to understand the SEO affects.

In addition, what happen when I promote a site with inbound links to
"http://www. example . com" and "http:// example . com".
Does the link juice drain to one URL or two different ones?


Thanks

[incrediblehelp]

Pick one as your main domain that you want to internally link to and you want external websites to link to. Usually people pick the www one. Then 301 redirect the non-www to the www.

You do this to avoid duplication/canonicalization issues with the search engines.

[sharonjackson]

Search engines see
www.yourdomain.com and
yourdomain.com

as TWO DIFFERENT pages. I use an .htaccess direction to send the non-www one to the www one.

i.e.

RewriteEngine On
RewriteCond %{HTTP_HOST} ^yourdomain.com
RewriteRule (.*) http://www.yourdomain.com/$1 [R=301,L]
ErrorDocument 404 http://www.yourdomain.com

The only place this does not work well is on older servers (?) where the host directory is
http_docs or where a previous webmaster has built some weird configuration. Maybe someone else can respond to that.

[amnesia]

RewriteEngine On
RewriteCond %{HTTP_HOST} ^yourdomain.com
RewriteRule (.*) http://www.yourdomain.com/$1 [R=301,L]
ErrorDocument 404 http://www.yourdomain.com

The only place this does not work well is on older servers (?) where the host directory is
http_docs or where a previous webmaster has built some weird configuration. Maybe someone else can respond to that.

It has nothing to do with having an older server and the document root is completely irrelevent. The only time this won't work is if a) you aren't running Apache, and b) you don't have mod_rewrite installed.

More importantly that rewrite is pretty sloppy and leaves a lot of holes, here's a better way:

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.example\.com [NC]
RewriteCond %{HTTP_HOST} !^$
RewriteRule ^/(.*) http://www.example.com/$1 [L,R=301]

[carol]

Great, but what if you are on a shared Windows server? Are we out of luck??

[amnesia]

Great, but what if you are on a shared Windows server? Are we out of luck??

Apache runs on Windows too. In fact it runs on most platforms.

[getmea]

It has nothing to do with having an older server and the document root is completely irrelevent. The only time this won't work is if a) you aren't running Apache, and b) you don't have mod_rewrite installed.

More importantly that rewrite is pretty sloppy and leaves a lot of holes, here's a better way:

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.example\.com [NC]
RewriteCond %{HTTP_HOST} !^$
RewriteRule ^/(.*) http://www.example.com/$1 [L,R=301]

My site runs on an Apache server and sharonjackson's redirect works.

Question: can you please elaborate on the "holes"? I'm not questioning you; I'd just like to understand the code.

Thanks

[freetutes]

It is up to you to decide whether you have the www or not. Most people prefer their domain name with www.

As incrediblehelp says you should do a redirection from non www to www or from www to non www. This is to avoid duplication issues with search engines. If you have backlinks to www.example.com and example.com and if you have done the 301 redirection for www or non www version then you will have no problems.

[amnesia]

My site runs on an Apache server and sharonjackson's redirect works.

Question: can you please elaborate on the "holes"? I'm not questioning you; I'd just like to understand the code.

Thanks

Yes it works, but only for urls that match the domain by itself, and only in a case-sensitive fashion. "Holes" was maybe a poor choice of words, I simply meant it leaves out a lot of other instances. With her rule, http://MyDomain.com/ would not get rewritten, and neither would http://site.mydomain.com/. By using:

RewriteCond %{HTTP_HOST} !^www\.example\.com [NC]

you are saying that anything that does not match http://www.example.com/ (non case-sensitive) will be rewritten, so it covers all bases.

[ron angel]

Pick one as your main domain that you want to internally link to and you want external websites to link to. Usually people pick the www one. Then 301 redirect the non-www to the www.

You do this to avoid duplication/canonicalization issues with the search engines.

I have found the simple way around this is to use the full
SS Richard Montgomery matter on all internal & external links always.