Search Engine Optimization (SEO), is a methodical, low cost marketing strategy for growing business by leveraging search engine technology. SEO, part art, part science, is vital to attracting a targeted audience to your web site.
In other words, by manipulating information on a web site, SEO connects the Searcher with the information they are seeking quickly and effectively. Many talented Web Designers who create absolutely beautiful web sites, will not bother with SEO. And, they will not inform their client of it's necessity.
For well established businesses, who have grown by traditional non-technical methods, will often not go 'the extra mile' to take advantage of this low cost, powerful method of marketing.