The subconscious is the part of the mind that protects us from danger. We, for instance, have a natural fear of putting our hand into a fire. The part of us that prevents us from putting our hand into a fire is our subconscious mind. Fear of fire is of course a perfectly rational fear and it is entirely correct that we have such fears.
Some of our fears are irrational and these we call phobias and phobias can have a very limiting affect on our lives, like the fear of speaking in public which affects so many people. Phobias happen when our subconscious mind tries to protect us from something that we really don't need protecting form at all. This 'mix-up' is usually due to a bad experience in the past. For example a fear of dogs could come from being frightened by a dog as a child. You had such a negative response to this event that your subconscious mind decided that ALL dogs were bad and hence your fear/phobia of dogs.
Hypnotherapy is extremely effective in correcting this 'mix-up' by accessing the subconscious and reprogramming the overactive protective behaviour. You will be amazed how completely changed your life will be when you're no longer controlled by your fears.