Food products are created because we need to eat to survive but products that are popular with particular age groups, and therefore sell well, have been designed with a particular group of consumers in mind.  If a product is aimed at one type of person then it is said to be aimed at a particular 'target market'.  A main techniques to find out what people like to eat is to use a questionnaire - but you probably know from being stopped in the street by market-research people that answering a series of questions can be very time consuming and can be boring if the questions are not worded well.  The questions can also be difficult to answer if you only agree with a part of the question but have been asked for a 'Yes' or 'No' response.  For instance try answering the question "Do you like school?"
                              One answer might be "No" or "Yes"

" … well I like Science because we do a lot of practical work with Mr Green, but then I don't really like Drama because Ms White is too easy going with the class and those lessons are too noisy … but then she is really good at media topics because she used to work with film people…."      So answers can be complicated.