Traditional web positioning involves a selection of fixed key phrases that should improve website's rank in Google search results. The more general (and theoretically popular) words, the harder and time-consuming work. Usually, it is difficult for new website to compete with well-established ones.
Additionally, consumers' approach also changes. Research indicates that users more often type multi-word phrases into the search engine, in order to find more accurate answers. This trend results from the notion that the more general phrase you type, the less precise results you get. Then, the user must apply more time and effort to find what it is he looking for.
That is why long tail positioning is particularly effective on e-commerce or regularly updated websites with many subpages.