What is SEO , SEM and SES?

Search Engine Optimization (SEO) 

The process of improving the volume or quality of traffic to a web site from search engines via "natural" or un-paid ("organic" or "algorithmic") search results. 

Search Engine Marketing (SEM) 

A form of Internet marketing that seeks to promote websites by increasing their visibility in search engine result pages (SERPs) through the use of paid placement like pay-per-click and contextual advertising.

Search Engine Strategy (SES) 

A group of ideas that focuses on search engine marketing and search engine optimization.