Hi Can anybody tell me that extension in URL affect SEO? I mean to say what is better? www.example.com/hello.aspx or www.example.com/hello also i would like to know that which extension is better? .php .html .aspx please let me know ASAP so that i can plan my new project accordingly.
No it don't. Though its always a good practice to avoid using extensions (if you have the option) as in future, if you ever change the platform, you can avoid lot of trouble.
Yes I support poseidon in that case. extension should be hide if possible and try to make url short as much possible search engine does not like long url.
With wide usage of URL rewriting, extensions have more or less become irrelevant. I prefer to avoid them when I can.
As everyone says, they are all the same (at least for Google- I can't speak for EVERY search engine out there) but I personally like to rewrite each link to end in .html or have no extension at all.