Ask some Web companies about Site development or SEO and they’ll try to blind you with science and confuse you into thinking it’s a black art. No magic required although that would be fun. Google promotes pages it thinks are authority pages to the top of its rankings. It’s your job to create authority pages. In simple terms this involves writing content and building links. So, in simple terms SEO involves writing pages that use keyphrases, EXACT words/phrases people use in searches.
Google says: Think about the words users would type to find your pages, and make sure that your site actually includes those words within it. The Goal is always to make sure your website is showing up in the searches your future customers are using to find you.
Search Engine Optimization or SEO is the science of ensuring a website can be found in search engines for phrases relevant to what the site is offering. In many respects it’s simply quality control for websites. Having said that if there was ever an industry that was little understood by ‘outsiders’ it’s SEO.