Search Engine Optimisation (Optimization if you're Stateside) or SEO is a process by which internal and external aspects of a web site are adjusted to gain high search engine returns on key word and key phrase searches. Search returns are sometimes referred to as organic or natural.

The majority of web traffic is driven by the major commercial search engines: Google, Yahoo And MSN. Google attracts approximately 60% of worldwide searches at 37 billion, with Yahoo (8.5 billion) and Microsoft (2.2 billion). A number of country-specific search engine companies have also become prominent in their own territories; for example Baidu in China, Guruji in India, Yandex in Russia.

High placements invariably lead to sites receiving an increase in traffic. 78% of users abandoning their search if the first 3 pages don't provide an answer to their question high search engine placements are essential. 28% don't even consider scrolling past the 2nd page of results. High traffic can be converted to revenue through sales, advertising revenue, referrals, votes or whatever call to action is invoked on landing pages. Smart, professional Search Engine Optimisation yielding high organic returns (70% of search engine users prefer organic search returns to sponsored links or PPC) can deliver extremely powerful results.

Anyone promising "guaranteed top results", "submission to thousands of search engines and directories", "instant results", "permanent top positions" or such like, most likely doesn't know what they're doing and are worth avoiding. It is impossible for anyone to guarantee that your site number one placement unless they run the search engine results or unless the top ranking is for a keyword or key phrase that exists only on your site - a Googlewhack.

It's as much as anyone can do to prepare the way for high search engine placing by using best business practices to put into place the necessary conditions for success. Search Engine Optimisation is a dynamic discipline with engines regularly adjusting algorithms and external issues (over which you or your Search Engine Optimization partner will have no influence whatsoever) coming into play - for example, competitor optimisation techniques and the popularity and search engine kudos of sites that link to yours.

Search Engine Optimisation is an inexact science with experienced professionals like SEO-MAMA working hard to apply it as exactly as possible. High search engine placement is a moving target. Absolute guarantees are worthless in as much as yes, they can be given but either the terms of the search optimisation applied will either be so vague as to render the process worthless or so specific as to render the Search Engine Optimisation worthless. Cast iron guarantees do little more than illustrate a lack of Search Engine Optimization professionalism and understanding by Search Engine Optimisation practitioners and at worst deceive website owners in handing over cash for unrealistic returns.

Professional and successful search optimisation is a multi-disciplined process involving an astute combination of professional skills. Copywriting, web design, web development, marketing, advertising and analysis are all integral to a planned, focused and well-executed Search Engine Optimisation project.
A solid starting point about Search Engine Optimization projects is in defining the words and phrases necessary to attract relevant visitors to your site - your semantic space and the foundation of your campaign.