If it were an easy question to answer, fairies would not be the magic, elusive, ethereal beings they are! Experience and belief in fairies vary from person to person and from culture to culture. These days many people do not believe in fairies, or at least feel foolish if they admit that they might-just might- consider that they exist.
It is easy to say that there is no such thing as the fair folk (another name for fairies) when you are in a city street at midday, driving your car, shopping, or talking on the phone. It is very different matter when you are out walking, miles from anywhere, and you find a bank carpeted with cowslips that seem to sing in the sunshine. It is also very different when you are alone on the moors and the mist is falling, or ina wood at midnight with the full moon above you. There you eyes may well be inno doubt-no doubt at all, at least for awhile- that these magical beings are real. When we consider the enchantment of the natural world, we are drawing closer to a definition of fairies. It is best however, to take a cool, dispassionate look at different beliefs about fairies in order to be as clear as possible about what they are and are not.
The logical, "scientific" approach is not to believe in fairies at all, stating that they are a figment of the imagination in the most trivial sense: at best amusing, at worse an ignorant or naive attempt to escape from reality(or, alternatively, a product of too much of the other sort of "spirit"). People who take taht attitude do well to remember that science and logic have not explained everything, and believing that they can and will (note the word "believing") is actually a belief stance in itself. To believe that our current perspectives onthe Universe are some kind of culmination-that we have basically "got it right" and that all we have to do now is to fill in a few blank spaces in order to complete our picture of existence-is arrogant and conceited. It closes our eyes; and it can tempt the fairies to play thier tricks on us.
Some people take on a positive attitude to the imagination, and visualize fairies as symbols that arise from the unconscious mind. From this perspective, fairies are important and call for reflection, although they are no more "real" than last night's dream. (Dreams, of course, beg a whole set of questions themselves, but let us leave them to the one side.)