why my website have a long name in result of google search ?
it is mydomain/index.php?Vsid=aa6e27f34b4d31adf3b5c77606c1378c ?
while other website have a small address in their home page like www.theirdomain.com ?
You need to perform proper url name optimization, It will help in ranking as well as optimize your url names so people can easily understand which page they are. url name or url structuring is very important for search engine ranking. If you include keywords in url name then surly it will also help in ranking of those keywords…
What URLs do you link to within your own site? Do they look neat and tidy, or do they have long strings of meaningless nonsense?
A good solution is to use the <link canonical> tag. On each page, include in the <head> a tag along the lines of:
<link rel="canonical" href="http://website.com/example/page.htm">
, where the address given is the address that you want Google to index for that page.