Search Engine Marketing, or SEM, is a form of Internet marketing that seeks to promote websites by increasing their visibility in Search Engine Result Pages (SERPs) through multiple techniques some free and some that have a cost attached to them.

NOTE: The Internet’s apex body, Search Engine Marketing ProfessionalOrganization (SEMPO) includes Search Engine Optimization (SEO) in its definition of SEM hence, SEO and SEM are intertwined and both work towards increasing the visibility of specific web pages in Search Engine Result Pages (SERPs)
If you build a website, visitors will come really does not apply to Web sites. Marketing the Web site is as important as designing it.  For your website to get a steady stream of visitors you’ve got to constantly focus on how to get people to visit your web site and access its information if they don't know about it?
You need a consistent, planned, continuous, integrated approach to marketing your website on the Internet so that visitors can find it when they are looking for products or services that you provide. Also, you do not just want new visitors, you want return visitors.
There are several tried and tested techniques to market a website on the Internet.  In this series of lessons we will take a look at these techniques and determine what you can do to successfully market your website on the Internet, help in getting visitors to come to your website and a bit beyond that.
What’s addressed is:
  1. How can you get more visitors to your website?
  2. What can you do to stimulate traffic?
  3. How to ensure repeat visitors?
And stuff like that.
Many of the techniques in these lessons may be doing already, others you meant to do but forgot about in the excitement of crafting your website and adding content, still others you may never heard of.  There is a great deal written about website marketing techniques. You'll find tons of links pointing to articles about website promotion if you just Google for them. 
I do not believe that any surprising new ground is being broken here, but there definitely is a summarization of the most important techniques for marketing your website on the Internet spread through these lessons.