Social bookmarking is a method for Internet users to share, organize, search, and manage bookmarks of web resources. Unlike file sharing, the resources themselves aren't shared, merely bookmarks that reference them. Descriptions may be added to these bookmarks in the form of metadata, so that other users may understand the content of the resource without first needing to download it for themselves. Such descriptions may be free text comments, votes in favor of or against its quality, or tags that collectively or collaboratively become a folksonomy. Folksonomy is also called social tagging, "the process by which many users add metadata in the form of keywords to shared content".
You can just type this "Social Bookmarking" and you will get thousands of articles/blog posts/forum threads about this subject. If you have just started to the blogging world, then I would advice you to go through the first 10 pages what google shows after searching with the above words. I am sure you will get a complete idea of what it is after going through those pages. Here mostly people have different opinions or debates about the subject..
Social bookmarking is a Web-based service where users can create and store links. It is an increasingly popular way to locate, classify, rank, and share Internet resources. While Web browsers have the ability to bookmark pages, those links are tied to that browser/computer. Social bookmarking, on the other hand, is tied to an online account, which can be publicly or privately accessible. Based on the viewing properties and tags/categorization, these bookmarks can be shared and discovered by others. It is a way to share news, sites, and much more with a broader audience. Examples of social bookmarking sites are: del.icio.us, Digg, Furl, My Web, Reddit.
Social bookmarking has been explained by others and should be an important part of marketing your website. It works well and get results.
In a nutshell, Social bookmarking is to 'save' an interesting/important webpage that you find useful for reference in future, sharing with other who might also find it useful.
In my own experiences, social bookmarking is really nice for building backlinks and generating traffics. It is a nice channel for Internet surfers to share and find the recommendations basing on tags. So, it is really important to include your targeted keywords in your tags on those social bookmarking sites when you bookmarked some pages. Have a nice day,
I think bookmarking was originally intended to store your favorite bookmarks online, so if you were at work, a friends house, on vacation, traveling, etc. you could then access your bookmarks via the online service if need be. These days it seems to have turned to social bookmarking sharing or whatever you want to call it. It's more of a way to generate traffic and in some cases backlinks now. They can bring traffic, and backlinks if they are dofollow social bookmarking sites. Many have turned nofollow now. Still helpful for traffic, but they are kind of time consuming.