Many years ago when the Internet was a little brainchild typing a single word was enough to get the information that was then available in the net. Nowadays when you type a single word you get million results. And what do you do in this case? It is self evident that using a whole phrase is the way out. For instance, if you type "web marketing" you can have much more results then if you type "UK web marketing". Nowadays visitor become more specific and consequently web promoters should take this into consideration and create specific and more relevant key phrases to boost their sites' ranking. However too complex phrases are not popular and can lead your site to fail in search engines results. There is one more piquant suggestion to this. Do not ignore the fact that the majority of your potential consumers can write several words together or make some common mistakes while typing the name of the thing they are looking for. Not that it means they were poor achievers but better take it into account while creating keywords for your site.