I was reading an article from the Chomsky Reference website and found an article (Citation research) where the importance of FOCUS is made relevant in attempting to find out why internet search users input the words or phrases that they do, in order to find out more information on a subject or product.
Focus is a concept in linguistic theory that deals with how information in one phrase relates to information that has come before. Focus has been analyzed in a variety of ways by linguists. Historically, there have been two main approaches to focus – the generative approach and the functional approach. In the generative approach, the term focus is used to refer to words or expressions that are either prosodically or syntactically prominent, generally because they introduce “new” information. In the functional approach, the term focus is used to refer to words or expressions that establish coherence in the text or conversation.