The expression Search Engine Optimization is something of a misnomer as it is not the Search Engine that being optimized
. The phase describes the process of designing or modifying a website in order to achieve high ranking in search engines results pages (SERPS). Search engine company would say that web designer should simply get on with producing excellent content and making their sites easy to navigate and let the search engines get on with indexing the resulting pages. On the other hand it can be argued that the search engine algorithm designers have the best idea of what elements constitute a well designed website and by learning from their ideas we should be able to build better websites.
Ten years after the web entered the mainstream web authors are still using this or similar semantically challenged terms. Google, who originated the idea of ranking sites based on links, puts value on the text used in those links. Recognizing this, web designers wanting ti achieve high ranking in Google will strive to use meaningful anchor text and increase the hyper linking of their sites. So long as this isnt taken to extremes, which in any event Google could recognize and ignore or punish, this should improve the user experience.
Optimizing a website require some knowledge of what factors search engines use when ranking a page and how significant each of these factors is for a particular search engine. Search engine use a mixture of on-page and off-page factors. On-page factors include the ALT text field used in HTML image elements. Off-page factors include the number of inbound or back links to the website. Different search engine put different weight on each of these factors; the exact algorithms used are a closely guarded secret and change frequently. SEO experts spend a lot of time analyzing how important each of these is to a particular search engine. If all search engines were perfect then they would all return the most relevant results in the same order. However we are some way from this situation so designing a site that ranks well with all search engine is difficult. SEO experts will also base their decision on the popularity of a particular search engine. At present this often means designing for Google and perhaps Yahoo! and MSN Search. Where this is done judiciously the optimizations should not exclude high rankings with other search engines.