We don't realize it, but we all have an ego that we confuse with ourselves. However, this is not the self that we truly are. But this "personal self", which you usually call "I", or Pepe, or Juan...etc, is just a concept to which you give reality. That concept of what you are and what others are is simply a belief. A mere opinion of what you are, or others are, without being. That fictitious entity that you defend in yourself or that you attack in others, without even knowing it, is what we call ego.
Your ego therefore is not a physical entity, but a belief of what you think you are. It is a mental state that you have built on yourself and that changes with you. You defend it because you are unaware of its existence in you and the damage it does to you. The ego occupies the lower portion of your mind and is constituted as an energetic entity that presses for its food: bad thoughts and low energies of all kinds. The ego grows and feeds on hate, which is one of the many faces of fear (fear is the absence of love). And where there is love there can be no fear, nor can there be any other negative emotion.
As you give a lot of value to your belief in the ego, you make it important, and it makes itself present to you and seems to be true, real, but I assure you, you are not what you think you are. You are much more than your thoughts or your beliefs than what you have been told you are, and what you yourself have built hard. the ego is the personality you have received and forged for yourself, from your karmic predisposition, your genetic heritage, the teachings of your parents, relatives, teachers, friends, etc... The ego is, so to speak, your response to the world you have been knowing since you were a child. He is your castle, your refuge, the being you -erroneously- think you are.
The ego is a yoke that you carry from birth until someone shows you their presence in you. It is like a jailer that shapes your character, molding it from birth to death, and that is shown to others through your way of being and thinking that will be based on your experiences, beliefs and knowledge about this world that you see, the world of the ego. It's the black horse that pulls your carriage if you don't catch it, and it won't let you get away easily!! Believe me, getting rid of it is our job here in the world!
The ego is a false self that seeks to replace -and succeeds- your Profound Self, which is your true Self. It is the other horse, in this case white, that pulls your carriage. Remember Plato's charioteer myth. You probably don't know either, but your "true self" is your authentic self, who you really are. It is not modifiable, because it is already perfect. He is your Spirit, which has decided for some reason to manifest itself through a body, as a means of interaction with the physical world. The best thing you can do is let yourself be guided by it. Each and every one of us are spiritual beings, truly perfect luminous beings. There is no one better, nor worse, neither good, nor bad... but we play with the ego to all that. We are not physical beings, and the body is just a vehicle of expression, like a glove that we put on to be able to touch this world. We are energy, we are Love. Forgetting this has cost us dearly. It has cost us Heaven.