SEM is the wider discipline that incorporates SEO. SEM includes both paid search results (using tools like Google Adwords or Bing Ads, formerly known as Microsoft adCenter) and organic search results (SEO). SEM uses paid advertising with AdWords or Bing Ads, pay per click (particularly beneficial for local providers as it enables potential consumers to contact a company directly with one click), article submissions, advertising and making sure SEO has been done. A keyword analysis is performed for both SEO and SEM, but not necessarily at the same time. SEM and SEO both need to be monitored and updated frequently to reflect evolving best practices.
5. Higher Brand Authority. Interacting with your customers regularly is a show of good faith for other customers. When people go to compliment or brag about a product or service, they turn to social media. And when they post your brand name, new audience members will want to follow you for updates. The more people that are talking about you on social media, the more valuable and authoritative your brand will seem to new users. Not to mention, if you can interact with major influencers on Twitter or other social networks, your visible authority and reach will skyrocket.
LinkedIn, a professional business-related networking site, allows companies to create professional profiles for themselves as well as their business to network and meet others. Through the use of widgets, members can promote their various social networking activities, such as Twitter stream or blog entries of their product pages, onto their LinkedIn profile page. LinkedIn provides its members the opportunity to generate sales leads and business partners. Members can use "Company Pages" similar to Facebook pages to create an area that will allow business owners to promote their products or services and be able to interact with their customers. Due to spread of spam mail sent to job seeker, leading companies prefer to use LinkedIn for employee's recruitment instead using different a job portal. Additionally, companies have voiced a preference for the amount of information that can be gleaned from a LinkedIn profile, versus a limited email.
Facebook pages are far more detailed than Twitter accounts. They allow a product to provide videos, photos, longer descriptions, and testimonials where followers can comment on the product pages for others to see. Facebook can link back to the product's Twitter page, as well as send out event reminders. As of May 2015, 93% of businesses marketers use Facebook to promote their brand. A study from 2011 attributed 84% of "engagement" or clicks and likes that link back to Facebook advertising. By 2014, Facebook had restricted the content published from business and brand pages. Adjustments in Facebook algorithms have reduced the audience for non-paying business pages (that have at least 500,000 "Likes") from 16% in 2012 down to 2% in February 2014. 
Organic search (SEO): When you enter a keyword or phrase into a search engine like Google or Yahoo!, the organic results are displayed in the main body of the page.When your prospects search for information about your products and services, you want to rank highly in search engine results. By “optimizing” your site, you can improve your ranking for important search terms and phrases (“keywords”). You can also improve your rank by getting other important sites to link to yours.
Your Competition Is Already Involved. Your competitors are already involved on social media, which means your potential social media traffic and conversions are being poached. Don’t let your competitors reap all the benefits while you stand idly by. If, somehow, your competition is not involved on social media, there’s even more of a reason to get started—the field is open.
On April 24, 2012 many started to see that Google has started to penalize companies that are buying links for the purpose of passing off the rank. The Google Update was called Penguin. Since then, there have been several different Penguin/Panda updates rolled out by Google. SEM has, however, nothing to do with link buying and focuses on organic SEO and PPC management. As of October 20, 2014 Google has released three official revisions of their Penguin Update.