The largest search engines, Google, Bing and Yahoo, each have fairly simple programs to get started. You determine the key words or search phrase as well as the amount you are willing to spend (per click and/or per day). Most of them offer simple programs that require filling out a form and putting a certain amount of money down as credit. Like anything new, start small with paid SEM and add complexity (and budget) as you learn more and see results over time.

Website saturation and popularity, or how much presence a website has on search engines, can be analyzed through the number of pages of the site that are indexed by search engines (saturation) and how many backlinks the site has (popularity). It requires pages to contain keywords people are looking for and ensure that they rank high enough in search engine rankings. Most search engines include some form of link popularity in their ranking algorithms. The following are major tools measuring various aspects of saturation and link popularity: Link Popularity, Top 10 Google Analysis, and Marketleap's Link Popularity and Search Engine Saturation.
Probably the most well-known Integrated Vertical Search is  Google’s “Universal Search” –  although all of the major search engines have now adopted similar search formats. This is the practice of incorporating different types of results in the Search Engine Results Pages (SERPs), such as news releases, images, videos, etc., depending on the query.  This was a game changer for SEO when it was first introduced – it became necessary to create and optimize many different types of content because they all show up on SERPs. The term for this comprehensive approach is referred to as Digital Asset Optimization (DAO).