seolinkexpert

Search Engine Optimization (SEO) and Search Engine Marketing (SEM) are Two different things altogether.

Search Engine Optimization is what is done to your site to ensure that the end users have a friendly easy to use web site with Search engine Friendly(SEF) Menus and SEF URLS that Google, Yahoo, MSN and Ask.com crawl through and find your content.
SEO is the process of optimizing your website with keywords, web page relationships through links, and design so that you rank well in the search engines for the search terms you are targeting. This doesn’t cost anything unless you pay a professional SEO to assist you.
SEO is a more technical process than SEM and involves a deeper understanding of search engine algorithms.

Here is the list of AdSense related terms that you should know for sure:

Page impression: A page impression is generally the same as a page view but the number of page impressions can sometimes be different than the page views. This happens when the page is viewed by a visitor but the AdSense code is not executed for some reason (which means that the Ads are not displayed to the visitor).

Ad unit impressions: Whenever you get page impressions, you also get Ad unit impressions. However, the ad unit impressions are dependent on the number of ad units you have on your page i.e. number of ad units that get executed when the page loads on user’s browser. Note that the link unit impressions are also counted as ad unit impressions.