First, let’s look at what marriage is on a basic level. Wikipedia gives a good breakdown:
“Marriage is an institution in which interpersonal relationships (usually intimate and sexual) are acknowledged by the state, by religious authority, or by both. It is often viewed as a contract. Civil marriage is the legal concept of marriage as a governmental institution, in accordance with marriage laws of the jurisdiction. If recognized by the state, by the religion(s) to which the parties belong or by society in general, the act of marriage changes the personal and social status of the individuals who enter into it.”
People marry for many reasons, but usually one or more of the following: legal, social, and economic stability; the formation of a family unit; procreation and the education and nurturing of children; legitimizing sexual relations; to fulfill religious obligations; public declaration of love; or to obtain citizenship.”
So basically, marriage is a declaration of love, but on a legal, state and federal level it is a binding contract between two people, and when looked at as a union by the government, there are changes in tax status, beneficiary rights, legal status and the like. Basically, you can have the long white dress, a gazillion flowers and the priest, but if it is not filed and recognized by the state, you aren’t legally married. On the flip-side, you can marry and register with the state without ever holding any type of ceremony, kissing the bride or throwing rice.