You couldn’t expect to get on the first page of google with a general single word search term, for example if you typed in ‘buy’ you would recieve over 100 million returned results. Thats over 100 million people trying to use the word ‘buy’ to send traffic to their sites.

Now ‘buy’ is probably relevant to millions of sites out there and who are trying to sell something, but is too general for any internet user and they would never find what they are looking for.

Key phrases in Search Engine Optimisation  should be specific to your site and be obvious to what a user might type in to find what you sell or your site, for example if you sold ‘wool carpets’, you would want your key phrases to include such terms. (buy quality woolen carpets).