Search Engine Optimization is the process of improving the visibility of a website on organic ("natural" or un-paid) search engine result pages (SERPs), by incorporating search engine friendly elements into a website. A successful search engine optimization campaign will have, as part of the improvements, carefully select, relevant, keywords which the on-page optimization will be designed to make prominent for search engine algorithms. Search engine optimization is broken down into two basic areas: on-page, and off-page optimization. On-page optimization refers to website elements which comprise a web page, such as HTML code, textual content, and images. Off-page optimization refers, predominantly, to backlinks (links pointing to the site which is being optimized, from other relevant websites).

“Search Engine Marketing” was once was used as an umbrella term to encompass both SEO (search engine optimization) and paid search activities. Over time, the industry has adopted the SEM acronym to refer solely to paid search.

At Search Engine Land, we generally use SEM and/or “Paid Search” to refer to paid listings, with the longer term of search marketing used to encompass both SEO and SEM. Below are some of the most common terms also used to refer to SEM activities:

  • Paid search ads
  • Paid search advertising
  • PPC (pay-per-click) *
    • PPC (pay-per-call) – some ads, particularly those served to mobile search users, may be charged by the number of clicks that resulted in a direct call from a smartphone.
  • CPC (cost-per-click) *
  • CPM (cost-per-thousand impressions) *
    • Most search ads are sold on a CPC / PPC basis, but some advertising options may also be sold on a CPM basis.