Hey I heard having http://www.yourdomain.com is much better that http://yourdomain.com with regards to SEO How much of an effect this really has? How to add that www? im using wordpress (self hosting) Does it matter if you do that many days after your site started? any harms in doing it or not doing it? Thanks
you put the same URLs there then! If you mean using the www. version over non-www. version then you should if you have access 301 redirect one version into the other (usually the non-www. version) to avoid potential duplicate content issues
Just be consistent with whichever you use. So, if you want to use "www", ALWAYS use www. Conversely, if you choose to leave out "www", ALWAYS leave out www.
In your internal linking structure. In other words, don't link a banner on the top of every page to "http://yoursite.com", and a link the footer to "http://www.yoursite.com". When there is variation, you have greater chances of each path being indexed separately. Engines have gotten better, so it's not as much of a concern anymore, but I'd say it's always best practice to be consistent regardless.