"The set of techniques and methodologies devoted to improving organic search rankings (not paid search) for a Web site." (Mike Moran & Bill Hunt , "Search Engine Marketing, Inc", 2005)
"The process and strategy of presenting a business on the web to improve the ability of potential customers finding it through natural searches on search engines such as Google, Yahoo!, and Bing." (Gina Abudi & Brandon Toropov, "The Complete Idiot's Guide to Best Practices for Small Business", 2011)
"The process of improving the volume or quality of traffic to a Web site from search engines via unpaid search results." (Linda Volonino & Efraim Turban, "Information Technology for Management 8th Ed", 2011)
"techniques to help ensure that a web site appears as close to the first position on a web search results page as possible." (Bill Holtsnider & Brian D Jaffe, "IT Manager's Handbook" 3rd Ed., 2012)
"Search engine optimization, the set of techniques and methodologies devoted to improving organic search rankings (not paid search) for a Web site." (Mike Moran & Bill Hunt , "Search Engine Marketing, Inc", 2005)
"The process of writing web content so as to increase a page's ranking in online search results." (Faithe Wempen, "Computing Fundamentals: Introduction to Computers", 2015)
"its main function is to increase website visibility. The main search engines use algorithms to rank a website’s position and hence its overall position in the search results. In some instances it can be as simple as structuring the words on a website in a way the search engine operates. " (BCS Learning & Development Limited, "CEdMA Europe", 2019)
