What's the difference between submitting article and not submitting? If I wrote unique articles for my site/product, I add articles to the site, but do not submit, will Google give it PR=0? If I submit articles to press/article sites, then I think my article will be considered not unique by Google, is it?
Do you have a sitemap.xml submitted using Google Webmaster Tools? If not you should do that. It will give it an idea what you have on your site and it will crawl your articles on a daily basis. Worth trying: https://www.google.com/webmasters/tools/home?hl=en You can generate a sitemap here: http://www.xml-sitemaps.com/
Yes I have one, and i submitted. I am confusing about the UNIQUE meaning. Google likes Unique articles, but if I submit them to article/press sites, those articles will be not unique. Am I right?
I am not 100% sure but I think Google has a system in place where it knows where the article has originated from (where they crawled it the first time). Everything else will be considered a duplicate. Unique simply means there's nothing out there on the web that is similar to your article (unique phrases, wording, etc.).
Article submission is part of offpage optimization in which serve as conent update for your site. It was very effective because search engine can easy crawl new articles and it will give backlinks for your site.
The first purpose of article submission is not, and I repeat NOT, to get backlinks. Since the last Google panda update, backlinks from articles directories are virtually useless unless the directory is directly related to your niche. Second of all, putting your articles on your site first and then on article directories will make sure that the version on your site gets indexed first, so that will not cause any problems. Article directories are useful for syndication only, not for backlinks. The first goal of article directories is so that publishers can find content to put on their site or blog. This is why they were created in the first place, not to build backlinks. So when you submit to article directories, make sure that your content is tailor made for publishers first and search engines second.