guys i like to know that do ".biz domain" affects on the ranking of page and search results of a site?and do this helps to raise the ranking of website in search engines...
Ohhhhhhh yes it does - there are must more trust in .edu and .gov. Some domains like .dk are very hard to get sandboxed because there is a lot of trust with it (from Google).
there are varied opinions about it but Matt Cutts has clarified that Google is not biased towards any domain. If you buy .edu domain and host porn website then Google won't attach a trust to it.
Thanks guys for your replies. So what you think which domain extension I should go with, .com or .biz, for a local business directory?
Not exactly, the only difference is that .edu and .gov domains are not available to the public and google might think (nobody knows what google thinks) that they are more trust worthy. You can outrank any .edu and .gov site that hasn't been well optimized with a .com easily.
It's best that you can get a dot com or either dot net, even if it means long-tailed keywords. From what I notice, dot biz usually lose out in serp.