The ego is who you think you are. The ego is not real and does not exist, the only reason you believe the ego exists is because you believe that you are separate from everything else, this is caused by dualism. You may have heard of ego death, the truth is the ego can't die, because there is no ego. The "ego" is the separate individual that you believe yourself to be. The 'ego" is your identity, which is based off of your past (which is gone forever) your future (which never comes) and every belief or concept that you have of yourself. The "ego" will latch onto any man-made concept as to not be exposed for what it is, which is nothing.
Anything that you think that you are, is the "ego". How many women say "I'm a mom first", and "my kids are my life", or how about "I don't know who I am without my kids" You're not just a mom, that is only one small part of your overall being, but when you identify with just one aspect of yourself, you start to "lose" the rest of yourself. When you "lose" the rest of yourself, and your entire identity becomes being a "mom". You identify as a "mom", that is who you believe that you are. If something were to happen to your child, you would no longer be a "mom". You would lose your identity and more than likely fall face first into a deep depression.
How many men use sports as their identity? Men have their favorite sports team and will have all their possessions be covered in the marking of that team. Their identity is a "bear's fan", when the bears win a game, they feel amazing, because their identity is so wrapped up in the bears that it feels like they personally won that game themselves. When the bears lose, they become angry and bitter, just as if they had lost that game themselves.
Anything can become an identity or an "ego". It could be your gender, sexuality, religious beliefs, or literally any topic known and yet unknown to us. Even an "enlightened" person can use "being enlightened" as their identity. "Enlightenment" is just the realization that there is no "ego" or "separate self", its more than just knowing, but also understanding. If you don't understand what "enlightenment" is or don't understand there is no "ego" then you still have an "ego". A lot of us on the spiritual path tend to get a spiritual "ego", where our "ego" latches on to the identity of "enlightened" or "awakened". When in fact the "ego" is using that identify to keep itself separate and "alive". The reason so many people have a hard time understanding the "ego" is because they are trying to understand something which they believe to be real but is not real. The "ego" is an illusion.
When we have an identity that makes us different from "others", we experience ourselves as separate. When we experience ourselves as separate, that is the "ego". Now just because you believe yourself to be separate from "others" does not mean that you are. You reinforce the "ego" by believing in it and trying to fight it. You're literally fighting nothing. As Alan Watts said, "it's like trying to pick yourself up by your own bootstraps" or "it's like trying to bite your own teeth". Trying to kill the "ego" is an impossible task. You're just trying to kill the you that you believe yourself to be but that doesn't actually exist. Some of us need to try to kill the "ego", just so we can find out there is no "ego" to kill.
The "ego" believes itself to be separate, so the "ego" will do anything it can to prove that it is in fact separate. By following the "ego" you will never get anywhere, the "ego" will just find a new identity to latch onto. The "ego" will always leave you chasing and never let you find what you're seeking. People who are on a spiritual path or have experienced a spiritual awakening will usually go through something called "a dark night of the soul". This is simply when part of your identity vanishes. Most of us have a lot of identities but tend to focus on one or two specific identities, such as being a "mom" or a "bears fan". When a big part of your identity vanishes, it feels like death, in a way it is, a part of you "died" but it only "died" because you believed it was alive in the first place. The "ego" tells you that you are your identity and if your identity dies, you will die. That's not true, your identity is not who you are.
How do you tell what part of you is real, and what part of you is the "ego". Start by telling yourself that you are not alone and it's ok. Secondly the ego always needs or wants something, the real you doesn't need or want anything. The real you, has everything you need and want already, you simply can't see it because the "ego" lies and tells you that you don't. The "ego" says "I want" and "I need". The "ego" blames "others" and holds onto grievances and bitterness, the "ego" doesn't forgive or forget. The "ego" can't forgive, by forgiving the "ego" would vanish. It is only the "ego" that doesn't forgive. When you forgive, "others" start to become visible to you, which kills the idea that you are separate and alone, which kills the "ego".
Do you believe that you're the main character in your life? Do you believe that your life trumps all "other" life? When is the last time you truly did something for "another" person that wasn't about you? Even saying "I love you" to someone is about your "ego". It is the "ego" that need to make that known. The real you Loves without words, and you do it all the time without even being aware of it. Love is shown by actions, not by words. Mediation is one method of getting past the illusion of the "ego". Asking yourself "who am I" is another method of overcoming the "ego". Since the "ego" tries to convince you of who you are, by asking who you are, you can see past what the "ego" tells you that you are. The "ego" needs words to reinforce itself. The "ego" likes to talk about itself. People who have seen past the illusion of the "ego" a.k.a. "enlightened people" don't have a need to speak. They have seen that it is only the "ego" that speaks.
You could try taking a vow of silence, for a short period of time, whatever you think you can do, don't try to do more than you think you can, you'll just get frustrated and more than likely give up. Start with just ten minutes or so, you'll find out rather quickly how much the "ego" has to say and just how much the "ego" won't shut the hell up, making everything about itself. You'll see just how hard it is to stay silent. The reason that monks practice silence and mediation is simply to show you that there is no "ego". Your true identity is the overall experience of your life and only you can know what that experience is, therefore you are the only one who can know your true identity.
How do you tell if someone has your best interest at heart of if their "ego" is running the show. The "ego" always wants or needs something. If someone wants or needs something from you, that is the "ego". If someone doesn't want or need anything from you, that is not coming from the "ego". The "ego" will always tell you what you "need" to do. The truth is "you need do nothing". I Love You and Peace Be With You!