Hello,
File “index.html” is my default landing page on folder name “folder1”.
In seo terms, is inbound linking to the url “http://mysite.com/folder1” the same as linking to the webpage “http://mysite.com/folder1/index.html”?
Technically its the same page of course, but from pure seo aspect is google ranking the 2 urls in a different way? Does it count the inboud links to these 2 urls separately?
Thanks for your help 
If you have some links pointing to site.com/folder and some to site.com/folder/index.html, Google will treat them as two separate pages, and will treat the links as pointing to separate pages.
It’s a good rule to always avoid “index.html” and just give the domain/folder names unless you do actually need it there. First, it will improve your search rankings, for the reason above. Second, it makes it easier for other people to type in, and removes any doubt as to whether they need to include the index.html or not. And third, it just looks neater!
Thanks a lot. Is it important also on inside links (internal links between my pages only)?
Yes! You want all links to pages on your site to use the same format - Google will follow both internal and external links, and any time when there is any variation, you are likely to lose out.
(If you have to have different variations, or you find that some people are linking to the wrong format, you can minimise the problem with the ‘canonical’ tag … in the <header>, put <link rel=“canonical” href=“http://domain.com/folder/”>, with the URL in the preferred format.)
Many thanks. Thats a good help.