I have just write an article for my website. I have more than 100 articles sites. Can i post this same single article at all these 100 sites? Is this is good or spam (Duplication)?
Submission of same article may not be considered as spam but it would be useless and worthless to do the same as search engines may display a single result for the same content, traffic may change through different sources.
duplication is not spam. its your content and you are submitting to article sites that accept such submission so it is 100% legit method. you can submit the same article to 100 sites if you want but you will get lot better result if you spin the article and submit one unique version on each directory
But search engines counting my backlinks separately for each site. then how this is useless or worthless?