In the simplest terms, a "phobia" is something that you are afraid of without having a concrete reason. You might be afraid of flying, even though every time you have flown, everything has happened normally. You can even be afraid of flying never having been on an airplane. They use the term "irrational" to describe a fear that is not based in experience, but I am not fond of that word. It's dictionary accurate, but "irrational" has undertones that I don't think are fair. Reason or not, it's very real to you and that's what matters.
By contrast, a "fear" is something that you have a direct cause for. A dog bit you when you were eight-years-old. Now you are afraid of dogs. That seems pretty cut and dry. The problem is that one experience may have colored your experience with all dogs since. Maybe it's even changed the way you live, usually not in a good way.
Both of these things have two things in common; they trigger anxiety and they generally get worse with time. You get stuck in a reinforcement loop where you have some anxiety about something, fear, phobia or even anxiety itself, then you have a strong reaction, of course, the "worst case" scenario doesn't come true and your subconscious says; "There! See! We freaked out and it saved us! AGAIN! Job well done!" Cause and effect gets distorted, but your subconscious hates unknowns and taking chances, so the cycle continues. All the while patting ourselves on the back mentally for having avoided a tragedy.
“Fears are educated into us, and can, if we wish, be educated out.” —Karl A. Menninger
Fortunately, fears, phobias, and anxiety all react well to hypnotherapy. We can use exercises to allow your mind to react to the cause of your anxiety in a safe environment. With hypnosis, we can create a dog who can't bite or a plane that can't crash and make them very, very real. If you can imagine it, you can experience it. From there, you can view the threat from a distance, a very safe distance, waiting to deal with it until you are good and ready, but that tends to happen fast. People in a hypnotic trance tend to be VERY fast learners.
In Denial of Death, Ernest Becker explains that “animals, in order to survive have had to be protected by fear responses.” Some Darwinians believe that the early humans who were most afraid were most likely to survive. The result, says Becker, “is the emergence of man as we know him: a hyperanxious animal who constantly invents reasons for anxiety even when there are none.” It need not be this way. —Gavin de Becker
Overall, anxiety is generally just us overreacting to something. If we can recalibrate the meter we use to measure it, we can turn down the volume on anxiety. Most of the time, we know perfectly well that our reactions are out of step with the level of threat and getting that back on track makes all the difference.