Search Engine Marketing, or SEM, is a form of Internet Marketing that assists in promoting your website, by ensuring that your site has maximum visibility on search engine results pages.
Paid Search Listings
Although some definitions of Search Engine Marketing (SEM) include Search Engine Optimisation (SEO), the New York Times restricts the definition to 'the practice of buying paid search listings'.
An example of buying paid search listings would be Paid Advertising or Pay Per Click (PPC), the most popular and successful of these being Google's AdWords.
Google Adwords is an internet marketing product that allows advertising on the Google content network. The listings you see at the top of any Google search, above the free listings, or down the right hand side of the Google search page, often highlighted in yellow, are paid for, or more commonly referred to as sponsored links.
Google AdWords can be very cost-effective as YOU choose how much you want to spend per click, and how many clicks you can afford per month.