The following are popular SEO acronyms commonly used to describe various elements of the optimization process: KEI - [Keyword Effectiveness Index] - a measure of keyword effectiveness based on a ratio of number of searches to competition level. SEO - [Search Engine Optimization] - the process of improving the volume and quality of traffic to a website from search engines via ?natural? (?organic? or ?algorithmic?) search results. SERP - [Search Engine Results Page] - the listing of web pages returned by a search engine in response to a keyword query. Related Acronyms: These acronyms are not directly related to SEO, but rather Internet marketing in general. Having said that, they are often used in conjunction with or in the same context as SEO. SEM - [Search Engine Marketing] - a form of Internet marketing that seeks to promote websites by increasing their visibility in search engine result pages (SERPs). PPC - [Pay-Per-Click] - an Internet advertising model used on search engines, advertising networks, and content websites, such as blogs, where advertisers only pay when a user actually clicks on an advertisement to visit the advertisers? website. CPM - [Cost Per Thousand] (where M is the roman numeral 1000) - frequently used in advertising to represent the cost per thousand page impressions.