posting on social sites
 

Is posting on social networking sites for daily matters to rank your site high in search results?

it is effective for ranking but it is not the only way to increase the ranking of your site you can do something more
social book marking
directory submission
blog commenting
add posting

I don't know for sure, but many SEO site always mention that social bookmarking will give juice to your site, especially the one with High PR. I think it is worth researched. Thanks

Yes, For increase Traffic post your link on social site...