Social Bookmarking is an important as because of the fact that it allows users to store, manage the links they want to save, which can used as per need for the future.
Social Media Marketing is the process of reaching prospects and customers, and acquiring traffic and visibility through social media sites such as Facebook, Twitter, LinkedIn and many others.
SEM is a type of Internet marketing associated with the researching, submitting and positioning of a website within search engines to achieve maximum visibility and increase your share of paid and/or organic traffic referrals from search engines.