Does it make a difference if you put the "/" at the end of your url when link building www. mydomain.com or www. mydomain.com/ does it matter?
I wish I knew if it matters, but to answer your question, I leave it out. I can tell you it is best to focus on either: aerospacenews.com or www.aerospacenews.com but not both! If you've been at this a while use a page rank tool to find out which one has higher rank for your domain(s) and stick with that. There will always be some leakage (links built by others or via the SE's), but find which one is strong and make it stronger still. Good luck!
It doesn't make a big difference in SEO. It only saves some server load and aids the loading speed of documents.
In fact it does matter, with of without the slash, technical those could be two different pages. For instance when typing without the slash most web servers add automaticly a slash so the actual folder is with a slash. Check this thread http://forums.digitalpoint.com/showthread.php?t=53074 and the post by http://www.mattcutts.com/blog/seo-advice-url-canonicalization/ So I would suggest always use the trailling slash with linkbuilding.
It does not matter when you are using just the domain: when linking to http://www.example.com or http://www.example.com/ / is requested from the server but when you link to e.g. http://www.example.com/directory /directory is requested from the server and when you link to http://www.example.com/directory/ /directory/ is requested from the server
I usually place links without the trailing "/" then use a mod_rewrite directive to do a redirect server side.
well the page i'm asking about is a sub domain www. mysite.com/folder/index.php or whatever that's why i was wondering if the "/" was important to include
The question is not if it is important to include, the question is how you want it to be. You have to specify [for yourself] what URL's you want, and you can pick only one possibility. Then you can use e.g. mod_rewrite to make everyone use just the URL's you want. That's just how to do it, that's SEO.
The true answer is yes, it does in fact matter. (a previous poster on this thread mentioned this) Matt Cutts is a well known and respected Google Engineer, and he recently spoke of canonicalization of URLs in this blog: http://www.mattcutts.com/blog/seo-advice-url-canonicalization Permanent redirects on the server side can help force canonicalization on your site. One of the things I always do when I create a new site (assuming it is a PHP site on a Linux server) is edit the .htaccess file with 302 redirects as such: RewriteEngine on RewriteCond %{HTTP_HOST} ^mcpmedia\.com RewriteRule ^(.*)$ http://www.mcpmedia.com/$1 [R=permanent,L] This forces all requests to add the www to the beginning of my domains. Try entering just mcpmedia.com (with no www) into your browser and you'll see how it works. I think some people also force home page requests to the domain, so if you go to yourdomain.com/index.php it redirects to yourdomain.com, and people take it even a step further by always forcing request from domain.com to domain.com/ If you add all three of these redirects to your root .htaccess file, you can be more liberal with your link building. I still recommend that when building links you choose a format and stick with it, both in your internal and external linking structures.