How was the social institution originally formed? The answer can vary, however the community believes that social institutions originate from a kinship system. There is an expression which I quote from "Family Poems" ...... Even though you can say that you are only have a good friend but actually you have a lot best friend because you need everyone to fulfill aspects different from other people's personalities. For sure, your best friend is the person who best understands who you are through what you are think and say. You will always feel a sense of kinship with them, you can immediately continue your friendship even after you haven't talked to them for years. This is kinship. This book will explain social institutions, ranging from the understanding of social institutions, types and functions of social institutions, how social institutions developed. We will discuss the principles of kinship which starts from the nature of marriage, family and kinship; customary traditions of marriage, traditions of kinship systems, and social coating.