Why did I write this book? The obvious answer is that I wanted to share it with others whatever I have learned and whatever knowledge I have acquired so far. Every person wants to do good to his family, friends and society. But to make this world a better place, we have to contribute to the development of others, and that should be our endeavor. Therefore, I request you to share the knowledge of this book to more people, and bring more light into their lives. This is the meaning of our lives.