As a marketing strategy for increasing a site’s relevance, SEO considers how the search algorithms work with the different search engines, and also tries to discover what people search for, and how.
For example, they many not just search for one single word, but two or more words, also known as the ‘long tail’. (NB: Long tail can also refer to the length of a campaign on the internet, how it keeps on going even when it is no longer being actively promoted.)
SEO also takes into account common misspellings or typos; a smart SEOSEM/PPC manager will capitalize on this relatively easy and cheap traffic.
SEO efforts may involve a site’s coding, presentation, and structure, enticing the search engines little robots, which search each website in order to give their readers the best search results.
SEO can also involve tweaking problems that could prevent search engine indexing programs from fully spidering a site. Or to avoid duplicate content from one site to the next, which the search engines will penalize you for.