Why do we judge other people?

We judge other people maybe because we don't want them to be successful. Or we critisize them because they achieved something that we want to achieve. And we are finding fault from them that its not in them. In that case we derogatory others. I experienced being critisize and critisizing other peolple. But after that experience, I realize that nobody is perfect and I can learn from my imperfections. What is imperfection? Imperfection is the opposite of perfection, it is the defieciency or fault of a person. We can learn from our imperfection and apply it to our daily lives.