Thank You for sharing for ideas..

Social bookmarking is part of off-page seo, here we can make backlink for website it allowed to store and share own link for SERP purpose.

its simply bookamrking your site to other sites with little bit info sharing over there.

Social bookmarking is good for getting traffic to website, but not good for seo as they provide nofollow links.

Social bookmarking is a user-defined taxonomy system for bookmarks. Such a taxonomy is sometimes called a folksonomy and the bookmarks are referred to as tags.

Social bookmarking means submitting your url with specific tital, tag and unique url with a little description so that you can get some inbound link

We do social bookmarking to store our websites information, it will help us to improve website traffic. And Social bookmarking also help us to cache our websites easily.

Yes, its good for ranking.