Social Bookmarking sites can be accessed online because they are online bookmarks. In this basic seo process, the website is submitted on other bookmarking websites.
When we aim to rank our website or someone else website, we turn towards every way to rank it, whether it is profile submission OR directory submission. Off Page SEO is valueable and one of the best ways to get backlinks would be through social bookmarking.

Social Bookmarking Sites List
Benefits of Social Bookmarking
As already told, social bookmarking is one of the most effective ways of obtaining backlinks. If you are successful in obtaining backlinks, the people who will visit that bookmarking site, they will also visit your website.
Moreover, there is no doubt that on-page SEO methods such as SEO-optimized content are what Google refers to, but for a quite long time, Google also prefers the sites which get references from other sites, that builds their trust. If the site is getting referred, that means: it is worthy enough to catch the attention.